As I don't have an encoder on my lathe spindle, only a single slot for Mach3 threading, I would consider doing this on my mill using a thread milling type of process and a thread milling type of tool. It would give all the control needed to put the grooves exactly where they are needed and hand writing some code to do it would be quite an easy task. The biggest issue would be the depth the tool had to overhang in a deep bore, you would have to go shallow and do a number of passes. 1" should not be too bad. I don't think the profile of the groove is critical but the cross section of it may be.
