Alternately you can use the ':' operator to get the position of the TCP expressed in the Frame you want.
ex :
Code
$GROUP[1].$UTOOL = $MOR_GRP[1].$NILPOS
$GROUP[1].$UFRAME = $MOR_GRP[1].$NILPOS
GET_VAR(ENTRY,'*SYSTEM*','$MNUFRAME[1,1]',frame,STATUS)
position = POS(0.0, 0.0, 100.0, 0.0, 0.0, 0.0, C)
tool_in_frm= frame:position
tool_in_frm should have the [0, 0, 100, ...] coordinates calculated in the user frame.