custom menu options with multiple lines of G-Code

Marlin has no documentation.

I would like to add load/unload scripts and a manual level script to my menu system on my Kossel. I tried it with the original firmware that Folger provided, and I couldn't figure out how (if it was possible) to pass it multiple lines of G-Code with one menu item, either by writing a function or in the menu item call.

I've upgraded to release candidate 8, and I just want to know if anyone knows how.