I know this is a really old thread and possibly no one cares anymore but i’m sure if someone finds this they will benefit from knowing that the tool mentioned by Jesse in his first post called markerTool does in fact do the job of lifting markers from the video track and moving them to the sequence level. First you must export the sequence to an XML file by right clicking on the sequence or using the “file” > “export” menu. Then inside markerTool select the operation you want to perform EG “Lift video markers to sequence level” and open the XML file you exported. It does the process completely silently but if you re-import your markers to FCP they should now have moved.
I used this tool to great success when trying to get a lot of video markers from 50 or so sequences into Adobe Audition to export the marker ranges to MP3. Apple products are very poor tools for functionality, they have such limited versatility. Adobe Creative Suite has saved me so many hours after the laborious task of getting files from poor software such as FCP into the Adobe CS.