You're wanting to enter it on the 1120S?
MT goes in Screen 49.382
OK goes in Screen 47.041 (royalty withholding)
On the 1040, in Screen 20.2, under Credits and Withholding, Credit for State Withholding paid before 12/31/19 (or after, if you believe that to be the case), at the very bottom of that subsection.
My non-residents file composite entity returns for MT, but on a dummy return, the presentation looks good with that input (it shows up as K-1 withholding on Page 11). I've personally filed OK returns with that data entry and had no issues.
I was trying to enter it on the individual state return from the S Corporation K-1. I finally found it the passthrough K-1 entry on screen 20.2, line 13. I was just overlooking it. Thanks for all the replies.