Thanks for the help people.
It took a few hours of trial and error but for those who want to know, here's how you install a GB ROM (in my case Calk v2.9.2) from a stock unrooted ICS ff18:
- download the el29 Odin file here: http://forum.xda-developers.com/show....php?t=1433101
(make sure all drivers are downloaded and installed)
- Run Odin el29 (this will get our ICS ff18 back to GB el29 BUT your phone will be glitchy. Do a factory reset and the phone should start up and function correctly).
- Now, install CWM for el29.
- In CWM install your ROM. In my case I installed Calks v2.9.2 so i had to download and run his "wipe all", (I forgot to do this the first time and it I got stuck on the galaxy boot logo), then install ROM.
LG G2 - Sprint