I don't think such tools are possible with FCPX. Unlike in the QuickTime days, codec support has to be hard-coded into FCPX itself as far as I'm aware.
You have two options:
1. Use Resolve as your NLE because it supports DPXs natively and can interpret them as clips.
2. An offline-online workflow where you generate offline QuickTime movies with timecode and then match them back to the DPXs later.
My software:
Pro Maintenance Tools - Tools to keep Final Cut Studio, Final Cut Pro X, Avid Media Composer and Adobe Premiere Pro running smoothly and fix problems when they arise
Pro Media Tools - Edit QuickTime chapters and metadata, detect gamma shifts, edit markers, watch renders and more
More tools...