[Day Date Time Format] Possible to translate Day

Would it be possible to have the day displayed in your own language?

Example:

Sat, 23-07-2011 21:43

I like to translate Sat into my own language.
Can that be done?

Where exactly?

Sorry.

I am using these Carterlake scripts.

In wxtrends.php for instance.
There are a few more pages where i set the date time format like that but the day is displayed in English.
I want it to be displayed in Dutch.

Can that be done?

is this using custom tags, or?

In Settings.php

$SITE['dateOnlyFormat'] = 'D, d-m-Y';

So I want the ā€œDā€ (Abbreviation of the dayname) to be translated in my own language.