[cups] sudo from lp account

[Narcis Garcia]

Hello, I'm trying to use with Debian 7 and Ubuntu 14.04 the feature of
adding a new printer to be treated through a ShellScript:

$ lpadmin -p "Epson1" -v file:///dev/null -i /tmp/driver.sh -E

This driver script is called by CUPS as "lp" user, when OneUser prints
something to "Epson1".
The script needs to perform a task as another user account, and I'm
trying to perform this with "sudo". I've added this line to sudoers:
lp ALL = (OneUser) NOPASSWD: /etc/cups/interfaces/*

The problem is that the execution hasn't permission to access
/etc/sudoers and "sudo" cannot grant permission for another's user
execution~session.

How can I reconfigure this behaviour?

Thanks.