I tested this across 30 channels with 48 bans for each, it walks through them in less than a second. ;];];]
Simply do /mode #chan +b ~t:<EXPIRATION>:<BANMASK>
The banmask is your regular wildcard-enabled nick!user@host mask. Expiration is a "timestring" (see below). Also, if you add a banmask which Unreal already knows it will emit an error. I'm not replacing bans simply because a person (and not some code ;]) should decide which expiration time should be active.
- /mode #chan +b ~t:60:Guest*!*@*
- /mode #chan +b ~t:1h5m:Guest*!*@*
- /mode #chan +b ~t:3d4h1m:Guest*!*@*
Get it here.