Custom WHMCS & Cpanel Communication

[gaigelama]

I want WHMCS to create an account for Cpanel

 

but the only thing it can't do atm is generate a username (which it usually does) but I have a somewhat custom Cpanel module setup. No subdomain, No emails, etc and it's only for space. How do I tell WHMCS what username to use and how do I tell whmcs to send the clients email to cpanel (I need it so cpanel can generate a ftp account from that email)

[gaigelama]

I couldn't find a edit button.

This is what I need help with now

 

I need to be able to create a custom username for cpanel and then have that custom username transfer over to the sub domain