FCP to create ".MXF" with DVCPROHD Codec and embedded captions?

We have FCP 7. We get captions from a captioner who uses CPC/Mac Captions as a .scc. We have been sending BetaSP for years but since we are now filming in HD would like to improve, so now the network is allowing a file via FTP. Their specs are file with captions embedded (708 for HD), an MXF wrapped file but video in codec is DVCPRO100 (DVCPROHD) & PCM for audio (either 5.1 or stereo x 2 (L+R+L+R). How do I create a DVCPROHD file as a .mxf file with captions embedded in a final cut pro world?