What I normally do (instead of using Material skills) is define vars (or floats or VECTORs) in lite-C and use those in the shader as follows:

var game_time = 0;
...
while(1)
{
game_time += time_frame;
wait(1);
}

Shader:

float game_time_var; // the _var / _flt feature is explained in detail in the manual

return (0.5+0.5*sin(game_time_var)); // pixel shader