You can just store the data in the vertices itself, then you don't have to sample textures.

Code:
typedef struct {
	float x,y,z;	// position in DirectX coordinates
	float nx,ny,nz;	// normal
	float u1,v1;    // first coordinate set, for textures
	float u2,v2;    // second coordinate set, for shadow maps
	float x3,y3,z3,w3; // third coordinate set, for tangent vector and handedness
	float tu4,tv4;  // 4th coordinate set, for additional data
} D3DVERTEX;

That's the D3DVERTEX vertex declaration from atypes.h - it's wrong though, you cannot really access and use tu4,tv4 like that. A8 is using the following instead:

Code:
const D3DVERTEXELEMENT9 VertexA8[] = {
	{ 0,  0, D3DDECLTYPE_FLOAT3,  D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_POSITION,     0 },
	{ 0, 12, D3DDECLTYPE_FLOAT3,  D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_NORMAL,     0 },
	{ 0, 24, D3DDECLTYPE_FLOAT2,  D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TEXCOORD,     0 },
	{ 0, 32, D3DDECLTYPE_FLOAT2,  D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TEXCOORD,     1 },
	{ 0, 40, D3DDECLTYPE_FLOAT4,  D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_TEXCOORD,     2 },
	{ 0, 56, D3DDECLTYPE_UBYTE4N, D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_BLENDWEIGHT,  0 },
	{ 0, 60, D3DDECLTYPE_UBYTE4,  D3DDECLMETHOD_DEFAULT, D3DDECLUSAGE_BLENDINDICES, 0 },
	D3DDECL_END()
};

Might look confusing at first but what it tells you is how the last 8 byte ("float tu4,tv4") are actually used.
I'd recommend using ent_buffers over ent_getvertex to get D3DVERTEX pointers. You could for example use the 2nd UV set to store data.

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