Tried up dd-wrt firmware few days back, I do really like it, but I do noticed my DIR-615 E4 Ethernet doesn't like my motherboard bundled Gbps Ethernet with dd-wrt firmware, and it's really un-stable, the link always up and down (Windows always report Ethernet link-disconnected!). So, I tried so hard to get into emergency page with IE8, Firefox with no success, the only browser can get into it is Google Chrome, but file-upload with Chrome always stuck!!! anyway, I found the SOLUTION!
**make sure you have the original firmware from DLink before you started the following procedure**
1. create a html file (dlink-recovery.html) with those following code (I got it dumped from Chrome! I've added "http://192.168.0.1" to form action)
<html>
<HEAD>
<META content="text/html; charset=iso-8859-1" http-equiv=Content-Type>
</head><body><form action="http://192.168.0.1/cgi/index" enctype="multipart/form-data" method=post>
<center><p><font color=blue face=Courier New, Courier, mono size=3><b> <font color="#FFFFFF" face="Courier New, Courier, mono">--
<font color="#0000FF">D-LINK</font></font><font face="Courier New, Courier, mono">Firmware Upgrade System </font></b></font></p><p><font color=blue face=Courier New, Courier, mono size=3><b>
<font color="#FF0000" size="2">
<font color="#FFFFFF">--------</font> Version 1.0.0.0 (Language Pack Support)</font></b></font></p>
<p><font face="Courier New, Courier, mono"><b><font color="#FFFFFF" size="2"> ------ -</font></b>
<font color=blue size=3><b><font color="#333333" size="1">
<font color="#000000">Date 2009/07/15</font></font><br>
</b>
</font>
</font>
</p><p>
<table cellPadding=0 cellSpacing=10>
<tr><td align=right>File Path</td>
<td> <input type=file name=files value="">
</td></tr><tr><td> </td><td>
<input type="submit" value="Send">
</td></tr>
</table>
</form><hr><ul><font face=Verdana color=red size=4>NOTICE !!</font>
<br></center><font face=Verdana size=1>
<li>If you upload the binary file to the wrong TARGET, the router may not work properlyor even could not boot-up again.<li>Support Flash Intel J28F128, MXIC 29LV640BT, ST 29W640FT <hr>
</body>
</html>
2. change your PC network adapter configuration "Media Type" to 10mbps full duplex in network adapter configuration->advance settings (hope you know where!)
3. change your PC network IP to 192.168.0.* (any number except 1!)
4. unplug the power from DIR-615, then press-and-hold the reset button while plugging the power back to DIR-615, hold the reset button until the power led-flashing!
5. use firefox to open the dlink-recovery.html which created from step-1, browse the original-firmware and submit. if success upload, you'll able to see the 'flashing' page with percentage counting up.
--good luck--