Sage have just uploaded a video which walks through the steps to configure level three credit cards (government or business purchasing cards) for use as a payment type when integrated to Sage Payment Solutions.
There are really only two main differences:
A checkbox on the payment screen to indicate “level 3” type card is being used
An added field for commodity code.
Commodity codes are used by corporate purchasing organizations to segment and
manage their total spend across diverse product lines. There is no universally accepted
commodity code standard, but the United Nations Standard Products and Services Code
(UNSPSC) is widely deployed.
In order to use level 3 credit card processing you must be on version 2013 or 2014 of Sage 100 ERP.