what for? you could just pass-in these item id as your parameters.
function script TestFunc {
message strcharinfo(0), "TestFunc called from "+getnpcid(0)+", with arg 0 "+getarg(0, 0);
return;
}
// item
501,Red_Potion,Red Potion,0,10,,70,,,,,0xFFFFFFFF,63,2,,,,,,{ TestFunc(501); },{},{}
// script
TestFunc(501);