Langkah pertama, masuk ke folder wp-includes >> locale.php. Lalu buka dan temukan :

function init() {
// The Weekdays
$this->weekday[0] = __('Sunday');
$this->weekday[1] = __('Monday');
$this->weekday[2] = __('Tuesday');
$this->weekday[3] = __('Wednesday');
$this->weekday[4] = __('Thursday');
$this->weekday[5] = __('Friday');
$this->weekday[6] = __('Saturday');

// The first letter of each day.  The _%day%_initial suffix is a
hack to make
// sure the day initials are unique.
$this->weekday_initial[__('Sunday')]    =
__('S_Sunday_initial');
$this->weekday_initial[__('Monday')]    =
__('M_Monday_initial');
$this->weekday_initial[__('Tuesday')]   =
__('T_Tuesday_initia');
$this->weekday_initial[__('Wednesday')] =
__('W_Wednesday_initial');
$this->weekday_initial[__('Thursday')]  =
__('T_Thursday_initial');
$this->weekday_initial[__('Friday')]    =
__('F_Friday_initial');
$this->weekday_initial[__('Saturday')]  =
__('S_Saturday_initial');

foreach ($this->weekday_initial as $weekday_ =>
$weekday_initial_) {
$this->weekday_initial[$weekday_] =
preg_replace('/_.+_initial$/', '', $weekday_initial_);
}

// Abbreviations for each day.
$this->weekday_abbrev[__('Sunday')]    = __('Sun');
$this->weekday_abbrev[__('Monday')]    = __('Mon');
$this->weekday_abbrev[__('Tuesday')]   = __('Tue');
$this->weekday_abbrev[__('Wednesday')] = __('Wed');
$this->weekday_abbrev[__('Thursday')]  = __('Thu');
$this->weekday_abbrev[__('Friday')]    = __('Fri');
$this->weekday_abbrev[__('Saturday')]  = __('Sat');

// The Months
$this->month['01'] = __('January');
$this->month['02'] = __('February');
$this->month['03'] = __('March');
$this->month['04'] = __('April');
$this->month['05'] = __('May');
$this->month['06'] = __('June');
$this->month['07'] = __('July');
$this->month['08'] = __('August');
$this->month['09'] = __('September');
$this->month['10'] = __('October');
$this->month['11'] = __('November');
$this->month['12'] = __('December');

// Abbreviations for each month. Uses the same hack as above to get
around the
// 'May' duplication.
$this->month_abbrev[__('January')] =
__('Jan_January_abbreviation');
$this->month_abbrev[__('February')] =
__('Feb_February_abbreviation');
$this->month_abbrev[__('March')] = __('Mar_March_abbreviation');
$this->month_abbrev[__('April')] = __('Apr_April_abbreviation');
$this->month_abbrev[__('May')] = __('May_May_abbreviation');
$this->month_abbrev[__('June')] = __('Jun_June_abbreviation');
$this->month_abbrev[__('July')] = __('Jul_July_abbreviation');
$this->month_abbrev[__('August')] =
__('Aug_August_abbreviation');
$this->month_abbrev[__('September')] =
__('Sep_September_abbreviation');
$this->month_abbrev[__('October')] =
__('Oct_October_abbreviation');
$this->month_abbrev[__('November')] =
__('Nov_November_abbreviation');
$this->month_abbrev[__('December')] =
__('Dec_December_abbreviation');

foreach ($this->month_abbrev as $month_ => $month_abbrev_) {
$this->month_abbrev[$month_] =
preg_replace('/_.+_abbreviation$/', '', $month_abbrev_);
}

Ganti dengan :

function init() {
// The Weekdays
$this->weekday[0] = __('Minggu');
$this->weekday[1] = __('Senin');
$this->weekday[2] = __('Selasa');
$this->weekday[3] = __('Rabu');
$this->weekday[4] = __('Kamis');
$this->weekday[5] = __('Jumat');
$this->weekday[6] = __('Sabtu');

// The first letter of each day.  The _%day%_initial suffix is a
hack to make
// sure the day initials are unique.
$this->weekday_initial[__('Minggu')]    =
__('M_Minggu_initial');
$this->weekday_initial[__('Senin')]    = __('S_Senin_initial');
$this->weekday_initial[__('Selasa')]   = __('S_Selasa_initial');
$this->weekday_initial[__('Rabu')] = __('R_Rabu_initial');
$this->weekday_initial[__('Kamis')]  = __('K_Kamis_initial');
$this->weekday_initial[__('Jumat')]    = __('J_Jumat_initial');
$this->weekday_initial[__('Sabtu')]  = __('S_Sabtu_initial');

foreach ($this->weekday_initial as $weekday_ =>
$weekday_initial_) {
$this->weekday_initial[$weekday_] =
preg_replace('/_.+_initial$/', '', $weekday_initial_);
}

// Abbreviations for each day.
$this->weekday_abbrev[__('Sunday')]    = __('Min');
$this->weekday_abbrev[__('Monday')]    = __('Sen');gg
$this->weekday_abbrev[__('Tuesday')]   = __('Sel');
$this->weekday_abbrev[__('Wednesday')] = __('Rab');
$this->weekday_abbrev[__('Thursday')]  = __('Kam');
$this->weekday_abbrev[__('Friday')]    = __('Jum');
$this->weekday_abbrev[__('Saturday')]  = __('Sab');

// The Months
$this->month['01'] = __('Januari');
$this->month['02'] = __('Februari');
$this->month['03'] = __('Maret');
$this->month['04'] = __('April');
$this->month['05'] = __('Mei');
$this->month['06'] = __('Juni');
$this->month['07'] = __('Juli');
$this->month['08'] = __('Agustus');
$this->month['09'] = __('September');
$this->month['10'] = __('Oktober');
$this->month['11'] = __('November');
$this->month['12'] = __('Desember');

// Abbreviations for each month. Uses the same hack as above to get
around the
// 'May' duplication.
$this->month_abbrev[__('Januari')] =
__('Jan_Januari_abbreviation');
$this->month_abbrev[__('Februari')] =
__('Feb_Februari_abbreviation');
$this->month_abbrev[__('Maret')] = __('Mar_Maret_abbreviation');
$this->month_abbrev[__('April')] = __('Apr_April_abbreviation');
$this->month_abbrev[__('Mei')] = __('Mei_Mei_abbreviation');
$this->month_abbrev[__('Juni')] = __('Jun_Juni_abbreviation');
$this->month_abbrev[__('Juli')] = __('Jul_Juli_abbreviation');
$this->month_abbrev[__('Agustus')] =
__('Agu_Agustus_abbreviation');
$this->month_abbrev[__('September')] =
__('Sep_September_abbreviation');
$this->month_abbrev[__('Oktober')] =
__('Okt_Oktober_abbreviation');
$this->month_abbrev[__('November')] =
__('Nov_November_abbreviation');
$this->month_abbrev[__('Desember')] =
__('Des_Desember_abbreviation');

foreach ($this->month_abbrev as $month_ => $month_abbrev_) {
$this->month_abbrev[$month_] =
preg_replace('/_.+_abbreviation$/', '', $month_abbrev_);
}

Langkah kedua, walaupun sudah berubah setelah dilakukan langkah pertama, namun susunan penanggalan masih menggunakan tata bahasa Inggris :

Sabtu April 24
th 2010

Untuk memperbaiki, masuk ke wp-content >> theme yang digunakan >> header.php. Lalu buka dan temukan :

<div class="date"><?php echo date_i18n ( 'l F jS Y',
false, false ) ?></div>

Lakukan edit sehingga berubah menjadi :

<div class="date"><?php echo date_i18n ( 'l j F Y', false,
false ) ?></div>

Proses selesai, dan penanggalan telah berubah menjadi :

Sabtu 24 April 2010

Selamat mencoba…. ;)