How are you thinking of doing it? While I think script is right solution here, I also think such a script might be painful to implement at moment, at least from AppleScript scripting context. You would need parse/write OPML.
If I add read/write access to row attributes then might be easier to write scripts that transform outline representation between iThoughts notes form and standard Bike form… and then use Bike’s built in OPML read/write functionality.
Maybe it’s not as hard as I think, or you have another plan. If not I can try to prioritize scripting access to attributes. Let me know.