Saluton
You can localize buttons on monobook toolbar by adding code like this
to MediaWiki:Monobook.js of your wiki.
if (wgAction == 'edit' || wgAction == 'submit')
addOnloadHook(function(){
if (mwEditButtons.length < 2) return;
// bold button
mwEditButtons[0].imageFile =
'http://upload.wikimedia.org/wikipedia/ru/9/9a/Button_boldru.png';
// italic button
mwEditButtons[1].imageFile =
'http://upload.wikimedia.org/wikipedia/ru/8/88/Button_italicru.png';
})
--
Kunlabore,
Aleksandr