Not an easy way. I think the only way would be for you to copy down the necessary Library and App Support folders/files for them to a flash drive/email and copy them to the other machine (effectively replacing the current ones with the new data). You could create an AppleScript that could do this, but that's a whole other deal. Then you would have to sync it to the touch because as far as I know there is only MM to sync info automatically to it, unless it's some other app in the App Store (they have some to-do apps that might function well as a calander or appointemnt book that sync across the web), but it won't be through iCal.
Next best? Use some online service. Doesn't Google have some calander? Though you would need wi-fi with your touch to access it.
Also, MobileMe may be $99, and there are free services out there that can do the same essential syncing, however, there is no single package and you would need to sign up/subscribe to multiple ones to do the same things as MM (however you just want to do one). When you consider it, MM comes out to about $8.25 a month for its services, which isn't all that bad.