Accessing Render API

I am attempting to port over a library that I had written for a custom game engine, which requires its own framebuffer.
To do this, I need to obtain access to the core rendering API, pushing transformation matrices and a vertex buffer to the core, and rending it out to a texture target with a custom shader.

Is this possible? If so, do you have any suggestions on how to go about accessing / implementing the features I want to use?

You will need to add AHUD to your scene and draw there using:

FCanvasTriangleItem triangles;
hud->Canvas->DrawItem(triangles);