First you need to be able to see your start menu. Try mapping your C$ share:
Open explorer and tap the 'Alt' key to bring up the old menu system. Tools -> Map Network Drive... \\127.0.0.1\C$Browse to the share you mounted. Hopefully your start menu is under something like:
\Start Menu OR Z:\Users\ \AppData\Roaming\Microsoft\Windows\Start Menu
Create a shortcut to the program you want to start in your 'Startup' folder and you should be good to go.