as long as the email server is accessible from the inet, you can. just setup the account just like it is at work. i suggest at home pull up the account properties and click the advanced tab and check leave a copy of messages on the server so when he goes back to work he'll download the emails again at work.
Yes, what he said. If you don't, he'll be intercepting his own e-mails-- meaning he'll get some at home, but if he wants to read said e-mail at work, it won't be there.