Do I have to have Lion on my Mac to move my MobileMe account?

I'm trying to get a friends iCloud account setup so he can share a particular iCal/iCloud calendar on his phone but I have encountered a few problems. The guy in question has a MobileMe account and when I try and to move the account to iCloud I am presented with a message that warns me I must have iOS5 on the phone, which is fine, and Lion on my Mac, which he doesn't have (unfortunately a few of his Pro Tools plugin wont run on Lion).

So my question is does it matter if I move his account to iCloud whilst still running Snow Leopard? Will iTunes, Mail, Calendars etc. work as normal and he'll simply miss out on a few features like Photostream? Or could worse befall me and I mess up access to his mail or something?

I could create another iCloud account to access the calendar and register it on his phone but this will become the master account and then it gets complicated with issues like Photostream.

Any help appreciated.

Update.
Went for it and everything seems fine apart from Mail where I had to configure a custom IMAP server and MobileMe SMTP to get iCloud’s email up and running in Snow Leopard’s Mail.app.

Got it all working but can't seem to send mail. Tried 'smtp.mail.me.com', 'smtp.me.com'. Anyone know what server I should be using at access iCloud mail? Do I need authentication etc?

Thanks

miata...do your sent items on your Mac running SL still sync with your iDevices and iCloud?