Just to put my two cents in, I have successfully flashed DIR-615 ver E4 with gargoyle following this steps, just in case someone find it useful.
I have a DIR-601 (Same hardware as DIR-600A) with AR7240 and it have been running gargoyle for some time now, it works pretty well but I don't like the poor coverage or Wireless in that router. On the other side I had a DIR-615 E4 running DD-WRT and it sucks, no working QoS, Hags after some time, etc... So I wondered if I could flash DIR-615 E4 with gargoyle since they have the same processor (AR7240) and similar wireless radio chips (AR9285 vs AR9287) so I started at OpenWRT to check for support and I found that the radio chip is supported from 10.03.1-rc4, and since Gargoyle 1.4.3 or 1.5.0 is based in rc5+, I figured that it was worth the risk

So, the steps are this:
1) Download Gargoyle for DIR-600A factory image (I have tested 1.4.3 and 1.5.0)
http://www.gargoyle-router.com/download ... actory.bin
2) Using a hex editor (I use XVI32 since its free) you have to modify the firmware identifier so the router does not reject the firmware as invalid for the model, open the file and go to the end, you will see the DIR-600 A1 identifier and you have to change it for the DIR 615 E4 identifier, then save the file.
You will see (DIR-600 A1): AP91-AR7240-RT-090223-00
You need to change to (DIR-615 E4): AP99-AR7240-RT-091105-05
XVI32 download link:
http://www.handshake.de/user/chmaas/del ... /xvi32.zip
3) Now you have an image that is ready to be flashed to DIR-615 E4, I used the DLink Emergency Firmware Flasher page but I guess it will work from the normal Web Interface too. To enter Emergency Flasher just disconnect power from your Router, set your IP to 192.168.0.2 (LAN Interface, never use Wireless to flash) and connect to the 1st LAN port of the router, press the reset button and keep it down while you connect the power to the router, wait for it (around 10 seconds) and the power light will start to blink in amber color, now use Internet Explorer (Chrome and Firefox don't work here) to go to 192.168.0.1, select the file we just edited and flash it.
4) You have to wait until the progress bar reaches 100% and the router reboots, then you can change you static IP to DHCP and wait for the magic to happen inside your router, after a minute or two you will have a working Gargoyle in DIR-615 E4 (IP 192.168.1.1).
I had some problems restoring settings from the DIR-601 router so don't restore settings from other model, its best to start fresh.
Hope it helps someone.
Eduardo Peccorini
P.D.: If trying this be sure that your router is E4 version, there are several versions of DIR-615 and they have different hardware, this will not work for other versions.