www.desaware.com has a lot of tools for hooking windows. i used to use vbmsg.vbx back in the VB3 days when I did AOL add-on programming. When i switched over to 32bit VB, I used spywork control. Ive always been a fan of dan appleman

I don't know if it helps you as I only had time to skim through your post (it's 6am here and I need to get to bed :)), but look into ReadProcessMemory and WriteProcessMemory functions. I remember trying to mess around before by creating pointers to addresses that seem like they should point to a variable in another program, but they didn't. I was curious again recently and found out that the two functions I mentioned is what you have to use. With them, you can directly read and write memory space in another program, given that you know the address that you want to play with. The functions are easy to use too; I easily made a little trainer-type program that I could modify variables in games with (like health).

As for sticking a whole function into the program's memory.. I don't know if this helps with that.