Hi Sean
Yes, basically you need to mimic a "web form" subscribe message.
http://www.xequte.com/help/mlking/index19.htm
See the "Web Form Processing" section under File > Options, Email Processing. There you need to specify the subject of your web form message, e.g. "Contact from Database" so that MLK can recognize and process it properly.
Use the web form schema button to specify the layout of the message. Basically the message will look something like:
Action: Subscribe
Email: nigel@test.com
First Name: Nigel
Last Name: Cross
Address: ...
Nigel
Xequte Software
www.xequte.com
nigel@xequte.com