@shyvam
Vendor tree information you need to extract from your base ROM. This is detailed in the guide I just linked. How to make your device tree is also mentioned there. I can't help you with this as I do not own a Desire X Dual Sim and I don't have the time nor knowledge to write a device tree for a phone I don't own.
Just to warn you, this is going to be pretty hard. If making CM ports was easy we'd already have the latest version
To even boot CM12 you will need to write/find new drivers as the MSM8225 doesn't support some stuff in Lollipop as far as I remember. This, among other things, is part of the reason that arslankirmani/nightwalkerkg/I started with CM11 as we could get a booting build relatively easily, but it still took a month. I would suggest starting with KitKat. No reference point on GitHub makes the job harder as well. You could look at our source here (
https://github.com/htclegacy and find the protou repos) but I don't know how close in hardware DX and DX dual sim are.