in the end, i chose to the WMI path, launching a process remotely with a VBscript file instead of psexec which would have been simpler (but was NOT working for some reason!).
regardless of whether you choose psexec or wmi, you still want to know that the dll got registered.
the advantage of the vbscript is that you can collect the processID and look it up using procmon.
so, step 1: create the vbscript file
taken from here:
step 2: download procmon
install procmon on the server you want to verify
step 3: run the vbs and verify on target server using procmon
filter procmon for processname regsvr32
process id generated from the vbs file