Hi Rex, Hi Tim,
Yes it is possible to do this I have recently done exactly this my self.
How I did it was to cut the stock rail long enough with some extra for triming back then mark the center of the rail so you can set up the point rail relief by placing this center mark at the joining end of the jig and marking the rail reliefs accordingly.
Remember the point reliefs will both be on the same side of the rail so take care with this part. I say this because I made a mistake on a rail, I marked the rail relief on one end turned the rail around and did the other end filed the reliefs and it look ok, then I saw my mistake and had to make a new piece.
Mark the first rail relief in the stock rail groove on one side of the jig, then mark the other end of the rail using the the stock rail groove on the other side.
The center work is as per the manual, I tried to do the straight closure rail,wing rail and gaurd rail as 2 pieces but your lengths and angles have to be spot on otherwise the rolling stock will not run smoothly, I think it is best to do these as 3 pieces. this is also true for the point frogs make them as normal frog and join them it is very hard to get the stright route length right as a single rail.
I also made a Double cross over with one of the points as a double slip, I found this a challenge but I got there, still need to finish it off, with the throw bars all round.
Cheers
Ray
PS Will upload a pic when I have finished the unit.