To my knowledge chanserv doesn't have an option in it's ban settings for it to remove the ban after a specified amount of time. This can be done with the regular /ban command, but that would require the client/bot that's running the code to have full ops in the channel. Additionally you stated that you wanted the kicks and bans to be performed by chanserv.
There is such a command, !tb [nick] [time] i.e !tb bob 3d or !tb *!*@123.456.78.9 3d
