Migrating from Moveable Type to WordPress Question

I host my own blog on yahoo small business. Currently it’s on moveabletype but I want to change over to wordpress. I’ve read up on the migration documentation but I’m not clear on how to install the wordpress blog while the MT blog is still active if I want my new blog to have the same address as the old one. Won’t this mean I’d either have to install WP to the same directory as MT (very messy I think) or actually delete my MT blog before installing WP. If so, won’t that mean downtime? Very Scary