I was looking for a way to only show certain themes on admin/build/themes page. I ended up adding some jquery to handle this. I created this script in a js file called theme_list.js.
var themes =new Array();
//Enter themes here into the array.
themes[0] = ‘theme_1′;
themes[1] = ‘theme_2′;
themes[2] = ‘theme_3′;
if(Drupal.jsEnabled) {
$(document).ready(
[...]
