Hi Joe,
AFAIK, "._line" or "_.line" (with the dot) cannot be undefined, so that you can always get the native function using this syntax.
You'd rather try :
(command "_.undefine" "_line")
then this (which souldn't work):
(command "_line")
(while (> (getvar "cmdactive") 0) (command pause))
and this (which should works):
(command "_.line")
(while (> (getvar "cmdactive") 0) (command pause))