Just heard that DXLab's WinWarbler has implemented Kenwood's KY command for sending CW via the CAT interface. Since PowerSDR also implemented the KY command, it should be a snap to send CW via SDRxKs from WW.
Because KY using an alpha string there should be no timing problems at all. Or more precisely any timing problems could be corrected inside PowerSDR.
A WW user would have to tell us how to select KY for CW transfer to PowerSDR.