Thanks to tailstock offsetting the tool moves along a line that creates an angle α (half of taper angle) with the axis of rotation of the orange work.
This method more suited for shallow tapers.
Approximately, the set-over S = L.sinα
L: distance between the blue centers
α: half of taper angle
The lathe is set to get when the chuck turns 1 revolution, the violet carriage moves L mm (thread lead). The tool is retrieved a little during the reverse stroke.