You need tipped tooling, HSS just won't touch these. You can use normal TC tooling I just use the diamond coated because of the work I do, I machine quite a few screws for other companies, ARC advertise my services others say they do them their selves.

Never tried a travelling steady, never found one that I can get into the right position. I do centre the ends and support on live centres. Sleeving up to a bearing size is OK but use an over size sleeve and turn to get concentric.