How to create user action for PO22.1

I'm trying to create a process flow that would do the following:

1. Display the PO info from PO20.1
2. Based on the user action, would release the PO using PO22.1 (Can't do it from PO20 without changing the Buyer Code on the PO)
3. Based on the user action, would "issue final" using PO20.1

I haven't had a problem doing steps 1 and 3, but I can't figure out the API call that would use a "R" in the FC field of row 1. I can do the call to display the PO on the first line, but can't get past that. Here is my API call:

_PDL=LAWAPP8&_TKN=PO22.1&_EVT=CHG&_RTN=DATA&_LFN=ALL&_TDS=IGNORE&FC=Change&PCR-COMPANY=2082&PCR-BUYER-CODE=F16&PT-PCR-PO-NUMBER=100553&_DELIM=%09&_OUT=TEXT&_EOT=TRUE

Anyone else done these types of calls using a detail forms?