How do use textures in vertex program? This is what I have:

ATTRIB vtco = vertex.texcoord;
...
...
OUTPUT  otco = result.texcoord;

...
...
# Use LIT to calculate lighting coefficients
LIT dots, dots;

# Calculate color contributions
MAD r0, dots.y, lightDiff, lightAmbt;
MAD ocol.xyz, dots.z, lightSpec, r0;
MOV ocol.w, lightDiff.w;

# Texture coordinates
#MOV otco, vtco;

I''m not passing in coords myself as I''m using sphere map tex coord generation, but even if I was passing them in myself I don''t know what I have to do with them in the program. What I''m doing above is just passing the incoming coordinates straight to the output vertex. Is this correct, it doesn''t seem to have any effect. Do I have to combine the texture with the color or something?