I built my T-slotted cross slide like this. You can either bolt the strips of steel to a Hex bar to set them at 60° for milling, or just file them like I did cause I couldn't swingt hat length on my lathe.
http://www.wrathall.com/Interests/ma...oss_slide1.htm
There is a link to an old article by Martin Cleeve which shows a lathe setup to face the 60° angle with a hex bar on the faceplate.