Changing keymapping in Ubuntu

I recently needed to remap the 2nd enter key on my macbook so that I would actually have an insert key (what were apple thinking?). Here's how I did it:

• xev | grep keycode (run this and press they key you want to map, this will help you determine its keycode)
• in a file put "keycode xxx = MyKey" in my case I had "keycode 104 = Insert"
• xmodmap keymapfile (the key should work straight away after this)
• to make the change permanent create ~/.xmodmap with all the key mappings you want and then go to System ▸ Preferences ▸ Sessions, click the Add button, fill in the Name and Description fields and put the following into the Command field:

xmodmap ~/.xmodmap