I'm pretty sure it won't work with 4.3.4. I didn't get back into AD until 4.3.5 and just used the updates that shilbert had done for 3.3.5 and recompiled everything. There's a pretty good chance that it would break your DNN install.

 

Realistically, I'd consider upgrading to 4.3.7 and forgetting about the fix for now. They made some changes from 4.3.5 to 4.3.6 that made the module run much better with the exception possibly being adding users from corresponding AD User Groups to DNN Security Groups if they've already got an account in DNN. I'm looking at that currently. I also found out that if the site is running in mixed mode (the Authentication line isn't uncommented in the web.config) then the AD Fix doesn't work period. I finally got the 4.3.7 source setup properly so that I can debug it and spent some time this afternoon going through it so that I knew exactly what it was doing. Tomorrow I'm going to investigate making some changes to that the fix works no matter what mode the site is set to on login.

If you really can't upgrade and you have a developer who can make the changes then I'd get the 3.3.4 source from http://www.getyourowntots.com and have them make the corresponding changes in the 4.3.4 source and recompile DNN. Then you'd just need to copy the updated .dll files into the bin directory on your production install. As always when making any change to DNN you'll want to backup the install (at minimum the .dll files you're replacing) and your database.

I'm going on what others were saying when 4.3.6 was released. I've looked at the code as well and didn't see any changes on the main pages used in Authentication but that doesn't mean something wasn't changed elsewhere. I'm currently working on updating the fix for 4.3.7. If people would stop interupting me to do my real job and if my VPC install would stop acting odd I might actually get to debugging the code. :D