Can I programmatically create a keyboard Shortcut to my add-in's in Revit?
Manualy, you can by adding a line to KeyboardShortcuts.txt located in the Revit Program folder. Look at these posts for more explanations: http://thebuildingcoder.typepad.com/blog/2009/04/addin-keyboard-shortcut.html and http://blog.rodhowarth.com/2009/04/how-to-create-keyboard-shortcuts-to.html
But as this file is stored in Program Files, you will not be able to write to it without being logged as administrator (Windows Vista, Windows 7). And Revit can lock it also.