All you need is an off the shelf
power splitter Molex -> 2x Floppy. (assuming SCSI->IDE adapter also needs floppy power)
Plug SCSI cable into SCSI->IDE adapter, plug IDE->CF into SCSI->IDE adapter. Connect splitter to the power supply and the cables to both to both of them. Prep CF card on the PC using WinUAE, insert into IDE->CF adapter. Put everything back together.
I'd probably consider making a slot in the HD8+ case so you can insert/remove CF card without taking the case apart. This will probably require building a harness to screw the boards into the case, or if you are more confident, gluing it in place.