Not sure what software you have. I'm using Nebulosity now, but I was successfully using Canon's EOS Utility and it's remote shooting feature. Live view is very handy too. You're only after focus, not image quality. Crank the ISO right up to max value (not sure what the 1000D is, ISO3200?) to speed up your focusing and get nice bright stars. Just make sure you drop it back down for imaging
Don't think the 350D will play nicely with Nebulosity without one of those Shoestring adapters - Nebulosity plays nicer with Digic III or newer cameras. The 1000D should be fine, though.