unfortunately you only can set an integer value via UMC. If you have a testsystem you can try the following commands on this system as a workaround. This will overwrite the value you have to set in the UMC anyway.
pkprinters -c 0.0082 <your_printer_name>
You can check the value with
You are aware of the fact that you have to enable print quotas and this only works for the lpd, ipp, http, socket and smb protocols.