Sorry, but at this time Hotmail offers pop3 and http (webmail).
I do see that an imap name imap.live.com exists in DNS, but it does not answer on the imap port 143/tcp.
Maybe they plan on offering it in the future, but at this time IMAP is not available.
You will need to rely on a primary and secondary computer setup with your iPhone until that time.
It's worth mentioning that multiple Windows computers can sync access to the account if they are running Windows Live Mail.
-Raymond