Set the work holder that the floating holder is going to be mounted in the way you normally would for a drill. I don't know what kind of floating holder you are using. We have a few adjustable holders for this type of machine. Next mount the tool. You shouldn't have moved the turret after lining up the work holder with the bar. (Or simply move it back to X0 for that tool.) Then indicate the tapered angle on the tap collet for zero runout, and then snug it down. Double check to see it didn't move. This is for an adjustable holder such as we use.
I purchased a very nice floating holder several years ago. It has never seen any service as it is too long for the machines we have with the exception of the SL-35 and possibly the 51 Conquest. There is no adjustment to the head on this tool. Set the work holder on zero like for a drill, mount the floating holder, and go to work.