How to migrate iPhone (particularly Calendar) to a new Lion Mac from Snow Leopard
I understand you want your iTunes library to be hosted on your main machine but not on your Lion machine. Bit of confused there.

FIRST OF ALL. Back-up all of your calendar, address book, etc. data before you proceed for any inconveniences that may happen.

Anyway. For migrating your calendar, contacts, notes &amp; etc. :


use the export features of those apps storing them on Snow Leopard machine and then import them to your Lion machine,
reset address book &amp; calendar on your iOS devices by connecting them to your Snow Leopard machine and un-checking syncing of those data and finally syncing them for changes to take effect,
setup iCloud on Lion and also on your iPhone and iPad so that you can sync those information with your iPhone and iPad.


NOTE: don't sync them through iTunes when you are on Lion because if you do so your iPhone and iPad will be wiped and then re-synced as you've said because those devices can be synced with only one iTunes library at a time. Since you won't be taking your musics with you, those will be gone if you sync through iTunes. Just use iCloud. But this also means that you won't be able to sync music and any other kind of media to your iPhone and iPad until you return to your Snow Leopard machine.

After your return then you should:
 - export those up-to-date calendar, address book, etc. info. on Lion,
 - import them to your SL,
 - remove iCloud on everything,
 - return back to old fashioned iTunes syncing.

I know it's a bit of a hassle but it's your only option as far as I can see right now if you don't want to move your iTunes library to your Lion machine.

BUT if you choose to move your iTunes Library as well then you may follow Apple's guides here to do so. And be careful when you're migrating. Don't just copy&amp;paste since iTunes' structure is complicated.

If you migrate then you can sync your calendar, address book, etc. through iTunes. But you gonna have to export&amp;import those to your Lion machine as well. So the first option stands out.

If you've any other questions, just let me know.