How to create a Workflow Custom Action in 7.7

I'm a new developper of a SugarCRM 7.7 application. It's now a very big application and we can't upgrade for the moment. I saw that there was a best practise to do it in SugarCRM 7.8. Howerver, I've not found any docmentation and anybody in the same case as me.

The idea behind this is to send a SMS with a time delayed to a customer. So i can't handle it with a LogicHooks.


So basically, my question is : What is the equivalent of the "Creating a Custom Action" Chapter of the joined pdf, but for SugarCRM 7.7 ?

Thanks,

Simon