The specific pack associated with the keyword "Custom Skin Pack for CS-SO -1.0 -" (often found on modding forums like GameBanana, FPSBeta, or CS-SO dedicated communities) typically includes:
"$basetexture" "models/weapons/v_models/v_m4a1/v_m4a1" "$surfaceprop" "metal" "$phong" "1" CUSTOM SKIN PACK FOR CS-SO -1.0 -
Example .vmt file (same name as .vtf ):