Believe it or not, I'm doing exactly that with exactly that right now.
I flashed it with DD-WRT v24-sp2 (05/27/13) mega (SVN revision 21676). Checking the isolated radio button for the virtual ssid does nothing - those clients can still see local network. What doesn't help is there is a Windows domain on this network and I am basically doing a corporate/public setup - not the hardware I would have chosen but I don't get to spend the money.
I've watched the videos on YouTube and I've read through the forums. I'm attempting to set up a 2nd DHCP server (by using it as an "additional" server on the router which is configured as a forwarder to the PDC. I don't have high hopes for that line of thinking. I too am interested to see if anyone has any information here.
I'm half tempted to just to ssh the damn thing and write some iptables rules but I would rather use that as a last ditch effort.