I'm having a bit of a problem with the scenario editor. I find that I can move any given spacecraft onto a landing pad, but I cannot move a spacecraft onto a runway. Is this possible?
Only by using the long/lat coords. Not the menus in the editor.
Try taxiing your ship the runway, making a quicksave, and then copy and paste the co-ordinates from the quicksave scenario into the scenario which you want to have start with that ship on the runway.
You can simply "land" the glider at the base via the scenario editor and then move it with the editor to the desired position.
The advantage over taxiing: You can enter the heading manualy and thereby be perfectly aligned with the runway.