To execute a program is relatively easy in VBA

Shell "c:\WINNT\system32\notepad.exe", vbMaximizedFocu

But to interact with the program can be difficult. I'm not sure if Messenger supports "Automation", but if it does, I don't imagine it'd be too difficult. Read about the CreateObject procedure to learn about launching and interacting with other applications

If you find that Messenger does not support automation, then take a look at http://www.mentalis.org/index2.shtml to learn about the Windows API. Tips on that, however, I believe are beyond the scope of this newsgroup

-Brad