ent_buffers(ENTITY* ent, var num, var lod, void** ppVerts, void** ppTris, void** ppAttribs);

"Returns the vertex, index, and attribute buffer of the entity mesh.
The buffers can be used to read or manipulate the entity mesh on a lower level than with ent_setvertex."

Further:

"ent - model, terrain, or wmb entity pointer, or level_ent for level blocks."

http://www.conitec.net/beta/ent_buffers.htm