Well you'll have to dive deeply into it to do the job of building a custom Android ROM. I just downloaded the kernel sources from the official JB (4.1) release, but I'm not sure how far I can get with that. Some experienced devs here posted that they would need Huawei's sources for KitKat to build a KitKat ROM, but I also have an Ascend P1 and I'm running a custom KitKat CyanogenMod build from the forums here although Huawei only released ICS (4.0) Kernel sources. I will have a try with a custom cross compiling toolchain of mine that I use for my Radxa Rock, but it's quite generic. I'll let you know how far I could get if at all.