Hi Branden,

Cro-moly is steel; it's just a specific steel alloy containing chromium and molybdenum.

The water bottle cage bosses and eyelets for the rack are called "braze-ons", and should be, uh, brazed on (not welded). An oxy-acetylene rig would be the best for this application, and for filler material you could use either brass or silver with lots of the appropriate flux.

The brazing procedure will be the same regardless of whether the frame is hi-ten carbon steel, cro-moly, manganese-molybdenum, or some other steel alloy.