Customize ProSites Checkout Page

I'm wondering if anyone within WPMU knows if this plugin actually works as a solution to make some customization of the prosites checkout page?

https://wpmu-hosting.net/whmcs/cart.php?gid=6

i found it with the WPMU forums:
https://premium.wpmudev.org/forums/topic/pro-site-how-to-change-text-or-block-color

but not much info is there - Vaughen seems to be the staff member that suggested it.
any thoughts?
best regards..... Eric