Rails (asset pipeline) and jquery.validationEngine custom rule

I have a custom jquery.validationEngine Ajax call that I can get working by manually creating a file called jquery.validationEngine-en.js, copying in the plugins code and adding my custom rule (see below).

From what I can gather, this results in the file of the same name pulled in via //= require jquery.validationEngine-en being replaced by my custom file.

I'm wondering is this the best way to do this? Is there a way to add custom rules to the //= require jquery.validationEngine-en in application.js file without having to create my own?

I hope I've explained that properly.