Syncing ipod to itunes
Your best bet would be to copy the iTunes library folder and the iPod backup from the computer that it was originally synced with to the macbook you want to sync to. This may get around iTunes wanting to force it to be step as new.

If you have never backed up your iPod then plug it into the computer you originally synced it with and perform a backup in iTunes. You can then use iTunes preferences to find where the backup was stored and copy this to the new macbook.

Then choose restore from backup on the macbook and theoretically it should re-setup the iPod in the same configuration as now and also allow you to use the macbook as the current syncing computer