See the usage of the DK portal to acherus.
Its only usable by the DK that spawned it I think .. or by DK.
Also you can make the code work only if the user is the owner of the object.
See GetOwner and similar functions.
dont know about the select thing ,.
You CAN code your own banking system. But that would require changing how the items are stored etc.
However atm the items are saved to the player inventory. Player has special slots in his inventory coded to fit the bank items so banking is actually a part of the normal character inventory slots - this is what you need changed.