Help with getting custom module+package to supply newer package than what's in the Guix Channel.

Hello. I am new to the Guix GNU+Linux distro. And I'm trying to get the latest version of Anki (2.1.65). However, the newest version is not in the Guix channel. I'm reading here that a simple edit to the education.scm file (the version var) would fix it. Unfortunately, the education.scm file in a Guix system is readonly. Unless they update the code, my only option is to make a custom module and package to supply a newer version. Though, I don't know how to do that (I'm a noobie). I just need help on figuring that out. Any help is appreciated.