Look in the documentation for the XR- series planes (they all have the same manual), there is a walkthrough for a launch. I think it actually serves an XR-2, but there are a few notes for the -5. The hardest part I've found is making a smooth transition from main engine to scram, then slowly backing off the mains until they are shut down. Ride the SCRAM until the pressure and temperatures dictate a shutdown, then light the mains again to orbit. It takes some practice, but the last time I flew a -5 I got to orbit with loads of fuel to spare. She's pretty docile with re-entry too.