The "persistent connection" setting was already set to N/A. I tried setting it to "no", but it didn't make a difference.
It seems that threaded mode is working alright. I think the reason it fails eventually has to do with the process running in debug mode. I haven't tried disabling debug yet, but I think that's where the problem lies.
In prefork mode, however, I am still not getting anything except 503s. I see all the python processes spawn, the socket is created, but they don't seem to be communicating with litespeed. Any other ideas?
Also, I've only tried on my development machine, which is an iMac. I'll try it on one of my linux servers tomorrow and see if I get any different results. Another alternative is that I could try rewriting their fcgi script to use the libraries you recommended instead if nothing else seems to work.