[Sirtel]

I apologize if it's been answered elsewhere, I searched, but could find no definite answer. Is it possible to add multiple custom columns to epub or mobi catalog? Yes, you can replace Genre with a custom column, but what of multiple columns? You can also add prefixes and merge custom data with comments (and I'm very grateful for these options), but they are not sortable. I tried to make a composite column and replace Genre with that, but there is no option to replace Genre with a composite column... unless I missed something.
In short, I would like to know if such a thing is possible at all.
Thanks for any help.