No, not directly. However, if you right-click the clip in the timeline and select Edit in Adobe Soundbooth > Render and Replace, you should be able to transcribe the resultant WAV audio file and have it be attached to the MXF video. I'm assuming you have the Production bundle or the Master Collection, of course.
Sidebar: The transcription feature is horribly broken. Yes, I know the transcription accuracy is sometimes way out there, but it's generally close enough to jump to specific points, especially if you're editing to a scripted voiceover. The problem shows up when you try to use the "play" controls in the metadata panel once the transcription is complete. At least with my editing setup, the audio playback will take over, and I won't be able to stop it: Premiere basically freezes until the audio file gets to the end. Hope your experience is better.
Colin, thanks for the answer about the .MXF files.
As for the problem you had with the playback in the transcript window, here's what worked for me:
I rendered out the .MXF clips to .AVIs. This allowed the video to display (instead of just the audio waveform) in the source window and the the text to display in the transcript window. I did not experience the playback problems you described. Hope this helps.
Sidebar: I'm working on a documentary, so the speakers, while mic'd with good lavs, are not trained speakers. The transcripts are just barely usable (although some are very funny: "the city Shapiro Yes good deal this is a two part question eight what are you all the question response to one of the first one question is What have you on what you've done in the last eleven months to help cover four of the calls would be done OK so this is gruesome ").