Luckily, xHausx has kindly modified the stock driver to include N support. He provided me a copy of the driver and I turned it into a flashable zip.
This zip has been tested by me on the stock 4.24 deodexed ROM provided by xHausx available here. It should work on odexed version as well as any other 4.24 based ROM (like Fresh EVO 4.2 etc.). The 4.53 zip has been tested on the stock OTA 4.53 available here.
For 4.53 ROMs, please use the zips labeled with 4.53 instead of 4.24. The 4.53 zips have been kindly provided by ca1ne.
ALL OF THE FOLLOWING METHODS REQUIRE THE REPLACEMENT OF A DRIVER. NANDROID BEFORE APPLYING.
----Method 1: Flashing the zip----
-Turn off wifi.
-Reboot into recovery.
-Flash the zip '4.24 WiFi N fix-signed.zip' or '4.53 Wifi N signed.zip' provided below. If you use Clockwork 3/5 Recovery, it does not support amend scripting. You will need to use the edify version instead. Simply download '4.24_WiFi_N_fix_Edify_2011_0713_signed.zip', provided courtesy of Smurph82**. The 4.53 should work with Clockwork 3/5 Recovery. The zip will wipe cache and dalvik cache, so the initial boot will take a few minutes longer. Be patient.*
----Method 2: Manually replacing the driver----
This method is for those that do not want to flash a zip or cannot get the zip to flash.
-Download and extract the right zip file for your ROM. All 4.24 zips and 4.53 zips are labeled as such. Either zip should give you a 'bcm4329.ko' file.
-Move the 'bcm4329.ko' file to SD card on your Evo.
-Open Root explorer (or similar file utility with system partition capabilities)
-Navigate to '/system/lib/modules'
-(Optional) Rename 'bcm4329.ko' to 'bcm4329.ko.bak'.
-Now move the downloaded 'bcm4329.ko' from your SD card to '/system/lib/modules'.
-Change the permission of 'bcm4329.ko' to 'rw-r--r--'. It should match the permission of all the other files in the folder.
-Reboot to recovery.
-Wipe dalvik cache and cache.*
*I'm not sure wiping the caches is absolutely necessary, but do it just in case to prevent any problems.
**The edify version should work now. Thanks for the help, Smurph82.