Skrill payment page within an iFrame
Currently the Skrill gateway module sends a customer off to the Skrill page to input creditcard details.
The Skrill page in question can be embedded within an iFrame on a page within a WHMCS installation.
I have asked Skrill and they have said this is both acceptable to do and that the page will function correctly within an iFrame.
This would at least require a modification of the existing official whmcs Skrill gateway module.
This would make it appear to the customer that they are still on your website and would mean a more seamless' integration.
I hope I have been clear enough.