Gritz,
When you're filing your flight plan, you can select other start locations besides the active runway at the departure airport. After you have chosen the departure airport, click on the drop-down menu at the bottom of the screen that says "active runway" and you'll see all of the choices available for start locations at that airport, including parking spaces. This way you can get your IFR clearance before taxi and get your taxiing instructions, too!
