Ah yes my tried and true method for installing cooling lines. Starting with a 36" piece of 5/32" brass tubing I sharpen one end of the tube and chuck the other into my cordless drill. Keeping the speed low and the pressure steady I hold the tubing flush along the tub floor curving up to the drill and let the tube cut the hole in the bulkhead. Each time a bulkhead is drilled through you need to carefully back the tube out and cut off about 1/4" of the end (it'll have wood stuck in it) and resharpen.
