I don't think you need a JOB per se, just an e-mail or file.
The registered address of the list-owner sends the following
style of text to the listserv e.g., for user1@node1 and user2@node2
the following two-liner file would suffice (the "quiet " is optional):
 
QUIET ADD list-name USER1@NODE1 Joe User
QUIET ADD list-name USER2@NODE2 Josephine Userette
// EOJ
 
/Pete ([log in to unmask])  --  co-owner  LDBASE-L, TQM-L, CPARK-L, et -L
--
Peter M. Weiss         "The 'NET' never naps"             +1 814 863 1843
31 Shields Bldg. -- Penn State Univ -- University Park, PA 16802-1202 USA