A couple of ways to do this:
1) Reorder the list and just convert the ones you choose -- You can cut and paste rows that you highlight, so one thing you can do is move them around. You might find some extra text shows up in any "blank" rows, but that won't hurt anything. Then to convert a subset of rows, you just highlight them and pick F5 or Document/Convert from the menu, or click on the convert icon (right next to convert all).
2) Create a new list with copy and paste -- If you open the original list and highlight the rows you want, then choose "copy" (as in the std Windows copy/paste), then you can open another list (or create a new one) and paste into it. Voila!
3) Copy the ixl file and then delete the rows you DON'T want.
But in all those cases, I think you still have to go through the ones you want and set the parameters (including the destination).
I haven't tried this, but if you're comfortable with xml, you can probably just edit the ixl file in Notepad. Change one destination as a sample and look at the old and new destination information. Then do a mass find/replace based on that information.
Hope that helps
