Confirming, it works.
Used:
Server - Dell T20 (Core i3-4130, 8GB, 3x0.5TB for testing purpose, will be changed to 3x3TB)
Loader - Jun's Loader v1.03b DS3615xs
DSM - DSM 6.2.3-25426 (latest 6.2.4-25556 wont boot, tried install pat file directly and as upgrade of 6.2.3 too)
BIOS - CSM mode (UEFI loader boot, but network stays unavailable, previous version of bootloader work well in UEFI mode)
- create boot flash
- edit grub.cfg (VID/PID, MAC1, Serial Number, SetPortMap=4
- boot
- find.synology.com
- upload PAT manually
- restart
- config new NAS