'Native mode' means a process built into the program -- it isn't. The only native mode for Premiere is OHCI DV. But Premiere can edit with any number of other codecs, including ones that are installed with specialty cards -- DVCPro50 would count as one of those. I believe MainConcept offers a DVCPro50 codec ... what card you can use to transfer is another story.
If you can uncover a Windows compatible method for transferring DVCPro50, I'm sure you can edit it within Premiere. But not 'natively', as that term quite specifically refers to DV OHCI only in the case of Premiere.
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