MacHandler creates Icon on desktop with the same name as MacOS HD name, so make sure MacOs hd name side is different then your partition, I'm not sure if that's possible.
You could created hardfile to transfer your files and mount it as your second drive.
In the MAC handler icon's INFO, change the ToolType to ACTIVATE=2 and STARTUP=2
1 is for first boot drive, 2 is for the second.