Create a secondary data connection to the source list (where does it live, BTW? SharePoint? SQL?) Drag the data node for the secondary data connection onto the canvas as a repeating section with controls. Remove controls you don't want to see and arrange the others to your liking.
Upon form load query the secondary data source. The repeating section will then be populated with the items returned by the query. This will only read the items, though.
If you want to edit the items, then you need a repeating group in your main data source. After querying the secondary data connection, you need to copy the data from the secondary to the main data source. Edits can be done in the main schema, and you will need a submit data connection to write back the changes.
This is not out of the box InfoPath functionality but it can be done with code or with 3rd party tools like Qdabra Software's qRules.