I'm not quite sure what bind.exe is, but it sounds like you're already trying to bind the trojan to another file. Look for something called Stealth Tools (I think). It will allow you to add size to the exe, manipulate the signature, and a couple of other things. When used properly, it should be able to bypass AV signature checking.

From what I know of it, elitewrap is just like a self-extracting ZIP, so once you run it, it will extract the torjan and try to execute the trojan, but once extracted the trojan is un-modified so AV will still pick it up. It is also easy for AV's to add signatures for trojans wrapped by popular packers (UPX, ASPack, etc).

If you want to manually change the AV signature (the best way to do it IMHO), you can't randomly modify data in an executable; you have to either find some bytes in the signature that aren't valid executable data (i.e., 0xCC, 0x00, etc.) or if you have some assembly knowledge you can change the actual instructions without changing the functionality of the program. Of course you first have to find the signature which is pretty easy, it just requires a hex editor and some trial and error. I actually wrote a short tutorial on modifying AV signatures a while back, it's at http://www.craigheffner.com/security/Taking_Back_Netcat.pdf if interested. I also have a couple variations of netcat on my site, one with a modified AV signature and another that reads commands from a text file rather than from the command line which might help you out.

Of course this is all assuming that the anti-virus you are testing against uses signature-based detection (most do). If it uses heuristics-based detection, it may be more difficult to bypass.

Try some of the hiders/binders on this list.

http://www.tenebril.com/src/spyware/file-hiders.php

YAB is my personal favorite.

hth,
-dean-