As a side note, see the KB article here regarding the maximum cable length between a PMP450i and uGPS/cnPulse in case you end up using the AUX sync method instead of a CMM.
Also, now that the uGPS has been replaced by the cnPulse device, the cable is no longer an RJ12 to RJ12 for connecting the cnPulse to a CMM5. More information available here and here.