telnet newshost 119
You can usually just say "help" and get the following message:
100 Legal commands are : article [MessageID|Number] authinfo [user|pass|generic|transact] <data> body [MessageID|Number] date group newsgroup head [MessageID|Number] help ihave <message-id> last list [active|newsgroups[wildmat]] mode reader newgroups yymmdd hhmmss ["GMT"] [<distributions>] newnews wildmat yymmdd hhmmss ["GMT"] [<distributions>] next post slave stat [MessageID|number] xhdr header [range|MessageID] xover [range] xreplic newsgroup/message-number[,newsgroup/message-number...]