The underfoot client allows you to set characters in your guild as a 'banker' (under the guild window) which should allow them obviously banker status when it comes to the guild bank and setting permissions/withdrawing/depositing etc.
This doesn't seem to function, only the guild leader is able to do anything that a banker should be able to. The options are allowed to be selected (ie changing an item from banker only to public) by the characters who are listed as bankers, but it does not actually do anything.