Using GDI functions on hooked Direct3D applications?

Hey there!
I finally did it to hook Direct3D. Now I'm planning to do ingame menus for my trainers. Currently I only hooked the EndScene() function but I could hook any other additional function easily.

On some games I have trouble by using the generated fonts of Direct3D. My idea is therefore to use a Bitmapfont instead.
I already coded a Bitmapfont Engine using GDI and I don't want to recode it for Direct3D if its possible.

Is there a way to combine GDI with Direct3D? I already tried the GetBackbuffer() function of the device object but it doesent work because I had to set something in the present parameters. I read that this is a bad idea because the performance of the whole game will slow down.

Did anybody solved this already or could tell me what to do?

Ask Dave or Obama.