Here's some details about patchrom, and what I've done so far.
First up. https://github.com/MiCode/patchrom already has a note2 tree, so we can use that as a base for changes for the 317.
Have all the same pre-recs installed as you would to compile cm.
In linux you'll need to make a patchrom folder
micode doesn't yet have all the repo setup for jellybean, so I just downloaded the following zip tardballs and extracted them into their respective folders;
https://github.com/MiCode/patchrom_miui/tree/jellybean -> patchrom/miui
https://github.com/MiCode/patchrom_tools/tree/jellybean -> patchrom/tools
Once that's complete you can pretty much follow the developer guide here;
I highly suggest installing this as your source rom, (http://forum.xda-developers.com/show...ighlight=stock) installing it as a stock build first (no themes tweaks etc)
Create a folder patchrom/317 and start following the guide to create your stockrom.zip
Copy the following from the note2 folder into your new folder
Edit the makefile to update the directory references to your new build folder.
Run the make workspace to unzip and decompile the frameworks that are going to be modded.
By following the guide, with what you've done we're now at the firstpatch phase. That's what I'm currently working on as well.
The directions are a little convoluted so hopefully this helps.
When you run make firstpatch what it tries to do is automatically patch the miui smali bits into the framework/services smali files. Whenever it can't it'll create a *.rej file for you.
What you need to do is edit the associated file and manually put in the diffs from the rej files. Where we have this super great advantage is there's already the 7100 framework with the patched in rej in the note2 folder you downloaded earlier. So really you just need to compare that smali file against yours and apply the changes noted in the rej file. (tip. you edit the original files created during make workspace, nothing in the temp directory, just in the framework.jar.out folder etc)
Here's a really great post detailing an example; http://forum.xda-developers.com/show...&postcount=171
Boy.. that doesn't sound easy.. but believe me it's easy once you start looking at it.
Ok I've dealt with the *.rej files now what?
Holy congrats! Your a step ahead of me at this point Next up you just need to run make fullota. It *should* at this point build an ota you can flash from recovery.
copy to sdcard, reboot recovery flash and.. it should boot. Really I expect there should be little or no issues thanks to the 7100 work we've already borrowed.
Assuming it works, let's get it on github and shared with the miui team. That'll go a long way to making it a weekly build.
Good luck and have fun!
If you get somewhere, let us know.