Pully no. Tranny yes. You will probably end up melting the input seal, which you will replace anyway. If you get it too hot you will melt the case. No real science to it.
If it was me. I'd cut as much of the pully off the hub so you can work on it. Then start heating the hub and do the hammer trick. If that don't work, I'd cut it off as to not damage or bend the input shaft.
I'm not familiar with the 820's, but if you can take it apart and remove the input gear from the input shaft then you could take the shaft out of the transaxle and press the hub off. It would also be easier to work on.
Paul