Thanks to zedomax for the idea, and the original script that I ported over for the AHD.
Thanks to mattiadj For the original hack.
Thanks to Ryuinferno for his init.d install script!
Screen shot with 32Gb Card installed:
Amended Easier Instructions:
YOU MUST BE ROOTED and have SS3 installed FOR THIS SCRIPT TO WORK!
1) Download all of the attachments at the bottom of this post, and Unzip all attachments EXCEPT "memory_swap.zip".
2) Copy all files to your phone where you can get at them easily
3) Install file extracted from busybox-1.rar. When finished installing click open. Do the "Easy Install" option.
4) Install file extracted from "android_terminal.rar"
5) Copy file extracted from "term-init.rar" to root of sdcard
6) Launch terminal emulator.
7) Type: su
8) Grant SuperUser access if prompted
9) Type: sh /sdcard/term-init.sh
10) The script will run and follow the instructions!
11) Reboot your phone twice and navigate to /data...you should find a Test.log in there...If it is present, congrats, you have init.d support!
12) Reboot into SS3 and flash/install "memory_swap.zip"
13) Reboot, let phone settle for a couple minutes, go into settings, storage, and you should see that your Internal & External SDCards are now swapped!
DEVs feel free to use this in your ROMs, and don't forget to give credit to all those already mentioned in this thread.
Alternate Install Instruction Video thanks to zedomax: