WHMCS Add On - Display Content on Admin Client Summary

[Asjad]

Hello,

I need to build a WHMCS module able to display content to the clientsummary page on the administrator view.

I'm basically trying to add a couple of fields into the client summary view, that my module will create on the database.

As the existing WHMCS files that do this are encrypted, I'm wondering if anyone would be kind enough to point me to a reference. 

Appreciate your help.