It's simple and straight forward. Set up an email for your blog using the 'Blog Options' page on your Spaces account and that will be the primary email you use to send to whenever you need to create a new post on your blog. That's what I have been doing for a long time now when I am not near a computer and it certainly came in handy many times.
Think of that email as a direct link to your blog and it's available only to you wherever you are. It's certainly one of the many convenient options available free of charge right under your fingertips from Windows Live Spaces.
