You're an FTer and you don't have the miles to get to an INO location????
Seriously though, if you "deconstruct" the burger, (and be sure to order it without condiments, or rather, special sauce on the side), you should be able to heat it up using a pan or toaster oven...
But why not just buy some nice burger meat and some buns and make your own version? In-and-Out is good and all, but it is, after all, fast food. I could whip up a burger 100 times better in the time it would take you to get in your car and drive to a restaurant to get one (if you lived where they have INO).
Save your craving for the next time you're in LA, or LAS, or PHX, or wherever...