First, to clear all bans on a channel, you can do:
/chanserv clear #channel bansor see /chanserv help clear
Second, there is a supported module bundled with the core services, i.e.
cs_tban module. Load the module and do
/chanserv TBAN #channel NICK TIMEor see /chanserv help tban
Thirdly, there is another 3rd party module called
cs_tban_address which can be downloaded from the new modules site. Check that out
[Edited on 20-10-2006 by n00bie]