OK. So, here goes.
If all is set up as I think it is, sfnc is a Java program that can create NPC or alien stat blocks from user input. From the link above, you'll need to put all the files in the same directory for it to run correctly. (The "fred.sfnc" file is an example NPC, so it's not strictly necessary.)
It isn't (yet) fully-featured, but it can do enough to make simple aliens. I haven't done class grafts, templates, or spells yet, or specific weapons, and many special abilities are just names and don't display all the info the stat block would.
If you have any requests or suggestions, please let me know. If you have any questions, I'll be happy to answer them. [If the question starts with "Why didn't you ...", the answer is probably, "Because I don't know any better."]
If you're interested in the source code, please look at my github repository.