Hi Marc, ok try the attached script.

Instructions for installing a plug-in script command here.

Set one of these for the command on each arrow key shortcut, note there should be a space after "Rotate90RelativeToView" :

Rotate90RelativeToView Left
Rotate90RelativeToView Right
Rotate90RelativeToView Up
Rotate90RelativeToView Down

- Michael

EDIT: applied bug fix from Mik