Everything is possible in my opinion but. You may want to go the "free turbine way" . First a small turbine is running way too fast so you would need a gear system capable of handling an input in 100K rpm range. Not an easy one.. Then putting a load on directly on the shaft would obviously slow it down and raise the exhaust temp way too high.
I dont think a direct connection is practical and dont aim at "high power " generation.
The free turbine concept is much more convenient as the turbo charger based turbine becomes a gas generator Those gas in turn spin another turbine so that the gas generator is relatively unaffected by the load etc. Its foolproof in a way that the free turbine will only gives you what it can , all the way to a full stall without damage to the rest of the engine.
Don´t think it will work, the throttle response is too sluggish with a freepower turbine so the alternator will bog down when you apply an electrical load. And when it has caught up and you stop the load it will overspeed the alternator.
By all means try it out, with the right kind of ECU it is probably doable, but it will be a very, very fuel thirsty generator.