Not really. Lionel FasTrack is tubular and uses pins. It doesn't have a base you could put slip-on joiners onto, plus the rail height is different.
That said, you can shim the ScaleTrax up to the railhead height of the FasTrack and just butt the two pieces together and add jumper wires to maintain electrical continuity. If the track is securely mounted and properly aligned, things should roll between the sections smoothly.