Yeah, I had to cut it twice to make the slot. Basically I taped 2 Sharpie markers together (it's the perfect spacing), set the pipe against the wall and put a 2 by 4 up against the pipe and made the 2 lines all the way down the pipe following the wood from one end to the other. Then cut along the lines with a jigsaw running at a slow to medium speed with a metal cutting blade. Just make sure the blade is short so it doesn't hit the other side of the pipe. That's the best way I've found to do it. I tried using a circular saw, a air powered rotary cut-off tool, and a router before and the jigsaw was the best and easiest. I haven't tried cutting it on a table saw, but that could work with the right blade I think.
I actually looked into using metal tracks and found several places online that could do what they call "C" channel, which is basically a square tube with a slot already cut in one side. It was something not normally stocked and a lot of the times custom order on the dimensions needed for the system to work so it wasn't really cost or time effective.

I also found a local welding and metal fabricating shop that could sell me "C" channel but it was actually more expensive than the curtain track and it wasn't as smooth.  The Theater supply company where I finally bought the track pointed out that the shipping of the track is the most expensive part.  It has to be shipped common carrier and even a short distance ( about 90 miles in my case) was going to be 200.00 for shipping...cost more than the track...and I was sure it would arrive damaged.  It is quite light and fragile.  I finally drove into the city and picked it up.

I will remember your method for cutting the pvc..I'm sure there will be a reason to do so in the future.  I was going to try a table saw with a jig to hold the PVC from rolling and hope for the best.