Asking For Developer Help

I have lenovo s850
stock rom is : KK 4.4.2
Kernel v is : 3.4.67
MTK : MT6582

and i want to make for it :
android_device_tree
android_vendor_tree
android_kernel_tree

i need really help to make it please coz i want to build cm12.1 from source
i know every thing about how to build but i need my tree !!

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