I normally use autohotkey. Though, I haven't really sat down to make it too complex for multiboxing, but it's possible to do some of the stuff you're talking about. source is downloadable etc.
http://www.autohotkey.com/download/
Note it's not for super easy setting up, most of it is done via a scripting language.
I try to avoid Lavish software since their login registration thing is kind of annoying.