Working DSM 6
So I got DSM 6 (6.0.1-7393) working (volumes stay mounted).
Here's a VMware VM if anyone wants to try it.
You can use VMware Player to run it.
Just add a new SATA hard drive before booting.
If you want console access, use PuTTY to connect to the named pipe \\.\pipe\com_1 (speed 115200) to connect to the VM's serial port.
This is pretty much it: add a SATA disk, boot and go to http://find.synology.com, configure and you're done.
DSM 6.7z
not excatly what i thougt, the spk format is sorted into platforms (processor/chipset) with cetain name
the spk istself can be opend like a zip file and inside is a file INFO
there you find things like
arch="broadwell"
or
arch="bromolow broadwell"
or
arch="x86 cedarview avoton bromolow evansport"
it ssems that arch="x86_64" is universal? at least synology packages contain that
if your packeage in question does not contain the "bromolow" it will not show up on 3617xs
if you