HP4 Flywheel - Holding tool?

Is there a special tool available to hold the HP4 flywheel ?

If not, what have other people used to hold it whilst tightening the nut.

SIP must have some kind of solution for this !

OK, thaks for that, I’ll give it a go.

I made up a tool using a piece of flat steel, 40 mm wide, 6mm thick. Drilled a hole to take my socket on the flywheel nut. drilled a hole that aligns with the single hole in the hp4 and used a 5mm allen bolt as a peg. Works to specified torque, no problem.