Yeah...simple, tick "Manually manage music and videos" on your iPod page, on iTunes. This will save to your iPod and automatically be set no matter what computer you are on.
That's it, automatic syncing is pointless, is it that hard to select the music from your iTunes library and do it yourself? Also there's no risk of wiping your library if you wanna use it on another computer.
Personally I like having control over my iPod, automatic syncing with my library removes that privilege, plus when I wanna try new albums out I always put them on the iTunes library first, at least having it manual means they don't automatically get transferred to my iPod.