Hey that's not a bad idea! I'll have to think about it but I think that's doable.
An alternative that is already available, which may or may not work for you, is to create a project.4coder. One of the features of the project system is that you can specify commands that the default custom layer associates to the F keys. All you have to do is nagivate to the project file and <alt x> -> 'load project' and the commands set in the project file get bound to the F keys, if you want to change them around you can just edit project.4coder and redo the 'load project'.
At the bottom of
this tutorial page you will find a tutorial on setting up a project.4coder file.