Method 1: Using OpenGL's native multi-texture support (using semantics)

// In C++ File:

   // Identify the textures to use for the pixel shader...
    cgGLSetTextureParameter( g_CGparam_testTexture, g_testTextureID );
    cgGLSetTextureParameter( g_CGparam_checkerTexture, g_checkerTextureID );

    // STAGE 0
    glActiveTextureARB( GL_TEXTURE0_ARB );
    glBindTexture( GL_TEXTURE_2D, g_testTextureID );

    // STAGE 1
    glActiveTextureARB( GL_TEXTURE1_ARB );
    glBindTexture( GL_TEXTURE_2D, g_checkerTextureID );

   cgGLBindProgram( g_CGprogram_pixel );
   cgGLEnableProfile( g_CGprofile_pixel );

   // Draw primitives

   cgGLDisableProfile( g_CGprofile_pixel );

// In Cg File:

   uniform sampler2D testTexture    : TEXUNIT0,
   uniform sampler2D checkerTexture : TEXUNIT1

Method 2: Using Cg's special texture functions:cgGLSetTextureParameter, cgGLEnableTextureParameter, and cgGLDisableTextureParameter

// In C++ File:

   g_CGparam_testTexture    = cgGetNamedParameter(g_CGprogram_pixel, "testTexture");
    g_CGparam_checkerTexture = cgGetNamedParameter(g_CGprogram_pixel, "checkerTexture");

    // Identify the textures to use for the pixel shader...
    cgGLSetTextureParameter( g_CGparam_testTexture, g_testTextureID );
    cgGLSetTextureParameter( g_CGparam_checkerTexture, g_checkerTextureID );

    cgGLBindProgram( g_CGprogram_pixel );
    cgGLEnableProfile( g_CGprofile_pixel );

    cgGLEnableTextureParameter( g_CGparam_testTexture );
    cgGLEnableTextureParameter( g_CGparam_checkerTexture );

    // Draw primitives

    cgGLDisableTextureParameter( g_CGparam_checkerTexture );
    cgGLDisableTextureParameter( g_CGparam_testTexture );

    cgGLDisableProfile( g_CGprofile_pixel );

// In Cg File:

    uniform sampler2D testTexture,

    uniform sampler2D checkerTexture