Thanks for the suggestion, but not being a photoshop owner; I was hoping for another way.
If you print your cover through Photoshop and select "print to fit" on 8.5 x 11. It should be the exact size of a Genesis Case. You can get a copy of photoshop on the photoshop for noobs thread.
I'm sure the method already mentioned works fine, but I thought I share what I was doing. I printed off several covers last night that were originally sized for UGCs. I manually changed the dimensions to 10.625" x 6.75" and everything fit perfectly.