I have no idea what one would use, but if the track is mounted on a bridge, the ties should stay in place if they're glued to the bridge. If all else fails, you could use thin plastic strips between the ties, glued to the bridge, to keep them space right. A piece of 0.010 inch styrene, whatever width you like for tie spacing, should keep them from sliding.
If it was me, I'd go the other way. Cut the spacers and slide the ties together. It would waste half the rail, because there wouldn't be any ties left for the extra, but in the long run probably wouldn't be much more expensive than buying replacement ties. Years ago I actually did that with Atlas code 80 flextrak, before deciding that leaving one tie every inch or so, and replacing the rest with wood, was easier. With Peco's code 55, wooden ties probably WOULN'T be easier, so I'd go back to sliding the ties together.