You're right, it can't be done in DX9, i apologize, but it CAN be done with the GameStudio engine
If you go to page 2 of this Thread, you'll see MasterQ32 has done exatcly what i want to achieve, with the 3DGS A8 engine
He shows exatcly what i want to do, i just don't know where and how to start

@Kartoffel - So how will i be able to do these vertex transformations in order to subdivide (or undo subdivision) the mesh's faces, with the 3DGS engine? I can't find anything in the manual nor online regarding this subject. I've found lots of tutorials with C++ but i can't "convert it" to Lite-C, i just don't know where to find the necessary functions/commands and information about them.