Script to update REST response and submit the form within

Hi all.

I have a REST request that results in a HTML response with a creditcard payment form in it. I want to put some info in its <input> fields (ie VISA card number, card holder name etc) using a script and then I want to "push the submit button" using the same script, this to remove any manual test steps. I've tried to re-generate the request in a new request but failed doing this so I want to se if it is possible to use the response instead.

Any help is appreciated!

Br
Mats