Just installed xpenology with dsm 6.1 (ds3615) with juns loader 1.02b on the PX6-300d (6 drive NAS). Pretty straight forward using this guide to boot from usb.
GUIDE: Customer OS on PX6-300D
1) Had to plug the USB in the back usb port.
2) Entered the PID/VID/SN and mac1 and mac2
3) also required to enter: SataPortMap=6
After that it booted right up and installed DSM with the synology assistant. Working good so far with no issues and all 6 bays can be utilized.