Redirecting using IIS 5

[The2ndOmen]

I am not the normal webadmin so I do not know how to do this. Here is what I am trying to accomplish. I have a domain

http://www.mydomain.com

which is hosted on a iis 5.0 server. I have created a virtual directory for a promotonial website to be

http://www.mydomain.com/promo.

My company has registered a domain for the promo called

http://www.domainpromo.com.

I need to redirect this to

http://www.mydomain.com/promo

and if possible keep the url

http://www.domainpromo.com.

Is this possible or is there anyway to achieve this.