InfoPath 2003 Integration

If you have integrated the process directly with the InfoPath Form using the K2 "InfoPath Integration Process Wizard", then K2 would have automatically created an XML Field in the process based on the XML Schema of the InfoPath Form.

K2, via the Context Browser, then allows you to drag-and-drop XML fields and other artifacts into your destination rules, line rules and other areas.

If you have not integrated directly with the InfoPath Form, you can create a custom XML Field and provide K2 with the XML Schema. When creating an instance of the process, first set the XML field equal to the XML data coming from the InfoPath form and thereafter you can start the process.

Hope this helps in anyway.

BPMER -- Samuel's response is right on for K2.net 2003.  Note that if you want to assign multiple destination users by looping on a repeating XML node you'll have to drop to code.

With K2 blackpearl there are some other interesting options as well.  To get an idea of the possibilities, take a look at the following blackmarket project: 

Task Allocation Service Object
http://k2underground.com/k2/ProjectHome.aspx?ProjectID=37

The Service Object was written to provide various task allocation methods (for use in Destination Rules) based on popular algorithms. They are broken down into either Active Directory or Role-based methods. This project contains the full project source, as well as a document describing al the methods, the deployment of the Service Object as well as how to debug the Service Object. The complete list of Task Allocation methods are: Active Directory Methods (GetManager, GetDirectReports) and Role-based Methods (GetLeastWork, GetMostWork, GetRoundRobin, GetFastestUser, GetSlowestUser)