Unfortunatley, the flow import capabilities in Pega are limited to a handful of dated versions of the following industry formats: BPEL 1.1, CIF 1.0 and XPDL 1.0. The current version of XPDL is 2.2 which is very different from 1.0 as it includes BPMN 2.0 process modeling extensions; XPDL 1.0 support isn;t foing to help you.
There is only one way I know of that customers were successful with importomg process modesl into flow rules in a wholesale approach: (1) Export the process model in an industry standard such as CIF 3.0 (most modeling software supports that format). (2) Create a XSLT transform to convert CIF 2.0 to Pega public format (a proprietary export/import format for flow rules); (3) Import the XML file in Pega piblic format into Pega.
Because this effort involves creation and testing of a XSLT transform and includes a long cycle of testing and refactoring (the incoming flows all go into the same class/ruleset) this approach is only recommended if you have hindreds of process models that you want to import.