Hello. 
 
I want to configure a new payment gateway on my on-prem HC Panel. is this possible? Can you send me the related documentation for this? 

Yes you can easily integrate your payment gateway with Hosting Controller version 10 by following the steps as mentioned in the link given below :
https://hostingcontroller.com/Resources/Whitepapers/Integrating-New-PaymentGateway-In-HC10.pdf
 
I hope this shall help you. If you wish our expert team to integrate your desired payment gateway with Hosting Controller control panel then you can discuss it further by sending an email to support@hostingcontroller.com