By using a Taper Attachment. The taper is rolled into the attachment and the cross slide screw is coupled to it.
When the carriage is fed towards the headstock the taper is produced. The cross feed handle still controls getting into and out of the cut.
Provided the part is not too long, I thread mill everything including tapered pipe threads. It is easier, faster and I can cut a 1\"-32 thread to within one half pitch of a shoulder internal or external! To control cost, I make my thread mills out of hand taps. I use the Mach 3 Wizard supplied with my mill to generate the code.
Works really well.
nitewatchman