From what I can tell visual rpg is built around the latest visual studio, so why don't you just use visual studio? if the visual studio integration is poor, then that suggests the tools themselves are probably poor. If that's the case, why do you need to work with this proprietary dreck? there is no shortage of high quality database engines, web toolkits and gui toolkits (many of them open source)
if you are undeterred, take a look at the source for the wxSmith (a gui builder plugin for the wxwidgets library) and CodeCompletion plugins to get an idea of how much work you would have to do. You would also need to write a lexer