Hello,
sorry for probably naive question...
Is there anything I could do to make use of optware packages on KongAC's latest firmware running on R8500? In general, optware installation links (for previous versions) are either broken or for wrong plaform. Any chance to have the "opkg" made available somehow?
(what I miss really are btrfs tools so that I could do remote btrfs snapshots)...
Otherwise - amazing piece of work 
(been using dd-wrt since many hears now, and I admire its quality).
Got it!
Kong's firmware contains a special script that sets things up. This is the actual difference w.r.t the original firmware, as explained here
http://www.desipro.de/ddwrt/Readme.txt
In short, you need to use the "bootstrap" script that will set things up. Yet before, you need to make sure you mount something writable on the /opt partition.
And here you need to be careful: in the web interface you pass the UUID label of the disk to be mounted on /opt, and not a thing such as /dev/sda1
Once you execute "/bin/bootstrap" you will get the "opkg" command working.
Hope this might help you