We have installed one of the VS 2010 Express versions available to download, and tried to set up the environment. After a little research we found that in previous Express versions you had to modify the
*.proj.user file to include a start action (old Kean Walmsley post). That procedure didn't work on our test machine, but we copied a .vbproj config file from a debugging enabled project, and we realized that the key entries were
<StartAction> Program </StartAction>
<StartProgram> {AutoCAD Architecture 2012 path}\acad.exe </StartProgram>
in the
<PropertyGroup> for debugging in the .vbproj will give you the desired effect.
Now there is the debugger breakpoint issue and its possible solutions. On a quick test we could effectively set breakpoints, due to be using the same .NET version as the debugger in VS.
Let me know your experience!
Cheers