Just a quick guide from my installation of DSM 6.2.1 Update4, before I forget it. The process was much easier than I expected, thanks to all the contributions and sharing in this forum.
*** This guide required MODDED BIOS and a HP NC360T NIC ***
Hardware Setup
Flash kamzata's modded bios, use attached file to burn an USB drive with the modded bios, boot the server from it and let it completes the bios flashing
Install the HP NC360T NIC, I bought a used one in Taobao for 14 bucks
Load "Optimal Defaults" from BIOS, then
In Advance page, disable C1E Support
In Chipset page, disable the onboard NIC Atheros AR8132M NIC
DSM Installation
Download Jun's Loader v1.03b DS3615xs (Synoboot_3615.zip | 17.3 MB | MD5 = e145097bbff03c767cc59b00e60c4ded)
Download PAT file DS31615xs DSM 6.2.1-23824 Update4 (263MB)
Prepare the USB boot drive, I followed Polanskiman's tutorial to write the generated SN, USB vid and pid in to grub.cfg boot image then burned it to my USB drive (below steps also come from Polanskiman's tutorial, really recommended to read it through)
Boot the USB drive, select the 1st option (or just let it timeout in a sec), wait for 10mins then run Synology Assistant, your Microserver should be found as a "Not Installed" DSM
Right click on the found DSM and select install, browse to the download PAT file above. Installation will take some time (10mins for my 8TB drives)
Post Installation
Enable SSH login
Update packages
Add SynoCommunity package sources - http://packages.synocommunity.com/
Packages
Log Center
Storage Analyzer
Photo Station
Audio Station
Surveillance Station
Transmission
WIP
Using Webcam as an IPcam with Surveillance Station
Kamzata Modded BIOS - run HPQUSB.rar