I know this is a year old, but I had the same question and found out how, so wanted to share in case others search in the future.

Withholding from Line 16 of CO K-1 goes to Form DR0104CR Line 11. 

Enter it on Screen 53.261 Colorado credits under Colorado Refundable Credits line "Tax paid by composite return or SALT Parity election"

Be sure to attach the CO K-1 to return.