Here you go. First pic: the problem - how to prevent the pressure plate rotating - STM tool engages with the 6 semi circular recesses in the plate. Second pic: solution. Make a plate with bolts in it that align with the recesses. Gash chain drilled centre hole to allow 30mm socket to fit onto nut. Third pic: bolt plate to my 48t clutch holding tool Forth pic: viola!
Love it. Post it up here too: https://www.ducatiforum.co.uk/threads/home-made-ducati-tools-post-your-pics.76097/
Finally got around to installing my STM Evo Clutch using my home made locking tool...it worked a treat , no slipping or anything up to 190Nm torque!