Stretch Midi Notes Custom Action?

[crackinkid]

Hi guys,

I wanna create a shortcut to stretch selected midi notes 2x and 1/2 in the same way the mouse modifier (opt) streches notes. So the notes position is altered with the time stretch and not only the note length shortend or streched. I couldn't find any custom action or script for that :O
Any ideas on how to do that, would be greatly appreciated.