To add Dow Commerce as your webstore's payment gateway, do the following:
1) Go to 'Store Settings (Expert)' in your webstore's control panel.
2) Select 'Edit' on the following page.
3) Find the field labeled 'advset' and add this to that field:
<DowCommerce>TRUE</DowCommerce>
4) Still in your Store Settings, fine the fields for Merchant, Merchantid, and Merchantke.A‚A These values should be set to the following:
Merchant = 31AUTHORIZE31
Merchantid = <your Dow Commerce username>
Merchantke = <your Dow Commerce password>