How to put user accounts in different sub-domain than main install

Caio

I would like to put my users in a different subdomain than the install. Instead of

forum.technicae.net/profile/user

I would like it to be

user.technicae.net/user

how would I do that?

Edit: I have not yet installed the forum and the user url will display a bluehost message.

I would also like to put registration at

user.technicae.net/register

and login at

user.technicae.net/login

hbf

likely a creative use of .htaccess and routes... but i have no idea what or how.