Unfortunately, a Linux port for the PDF-XChange product line is unlikely at this time. Tracker Software would love to able to provide this option to our clients, but our development team is focused on enhancing and optimizing our product line for the 'conventional' operating systems at the moment. Developing Linux versions would be a huge undertaking and - at least presently - we do not have the resources available for it.
However, it should be noted that the PDF-XChange product line received a Platinum rating from WineHQ, which means our products will operate at a very good level of functionality via Wine. Our WineHQ rating can be viewed here.
Additionally, the portable version of our products do not need to make registry settings, which may make them more suitable to your needs. They are available here.