Ping
Sorry I am late to this thread, haven’t been online since earlier today, and at the moment only have my cell phone. So this is a quick note and I’ll try to write more later.
Shadowace is correct in that a combination of sed and awk applied in the context of a careful bash script, is probably your best tack.
Someone may have already mentioned this, but I will as well. You also wish to consider people who have made bookmarks using the mixed case URL syntax, meaning even if you get all the internal references lowercase, and the file name is lowercase, bookmarks will still fail. So I suggest that you record the names of the files in the mixed case format, and make a set of symbolic links that direct mixed case accesses to the lower case file names.
All for now, I’ll try to write back later with perhaps a sample script.