Can I use one on a nine speed set up?

Not sure whether the jockey wheels are different for the thinner ten speed chain?

Quick answer: no. Long answer: yes. You can bodge together a shimano mech with sram shifter by using a spacer on the mech. Google it.

Just found that Modification,

Hows about with Shimano XT shifters??

No (unless they’re flatbar road shifters and a 9spd mech).

Cool, old school clutchless rear mech it is then!