One-step sign up in Multisite

Has anyone figured out how to do a one-step sign up in Multisite?

I’m working on allow people to choose their username, email, password and a confirmation of their password, along with choosing their blog domain (subdomain), blog title, along with the captcha on one page, but I get errors thrown when I try and merge the two steps.

I’m running the Choose Password plugin, Pro Sites, and Anti-Splog (which is where I have the re-captcha set up.