As of today, the LJPOST client works without any major incidents. The whole code is pretty okay, but I'll have to work things out a bit. The bloody thing is leaking memory somewhere, and I have to plug things up. Gah. Damned C string management. (Oh yeah, C doesn't have real string management.)
I was planning to add a real scripting engine, but I've decided to go small for now. I'm working on a small language that'll allow me to use the client for basic batch processing. I was going to embed Python into it, but I realized that it would be better to just create a separate LJ extension for Python in the first place. Then I thought I'd use the ActiveX scripting engine (as per mart's suggestion). Hmm... will work on it.