How do I set up the TIFF colour separation?

Tick TIFF + white in Production files and the settings open. Choose a profile under "Separate for" (SWOP, GRACoL, FOGRA, Japan Color and others) or load your shop's own .icc file, which is remembered. Choose a rendering intent and black point compensation. Add up to four spot channels: White, Gloss or a named Spot ink, each from all the artwork or by colour.