Carrying off-the-body is sometimes the only method left to you, but it's by no means ideal. You cannot EVER let it out of your sight, and it's best to set it between your feet when seated.
There's the problem of presentation. You'll need to shop around to see what case will meet your needs. Figure out exactly where and how in the case to carry it, and in which compartment. Be prepared to set up or make compartments/dividers/holster supports from some stiff material such as cardboard or very thin plywood. This also prevents printing with softer cases. Be creative with "paperwork" that flops to the side to cover the gun compartment. Set it up so you don't have to go through closed zippers, but instead make it a simple reach and grab setup. Practice, practice, practice your draw.
Lastly, act and dress as "just another person" with your (covertly modified) nothing-special computer case. Remember the old submarine corps motto....Run silent, run deep.
