A first step should be to map the fields form the AD to a attribute in the SharePoint user profile. You can do this in the configuration of the Share Service Provider (Central Administration > Shared Services > User Profiles and Properties).
There you add a new attribute and define which AD field should be mapped to it. You can also define which fields the users are allowed to override (but only in SharePoint, it's only a one ways synchronization) and which one are read only.
This blog post shows how to configure the SharePoint search to be able to search users by a custom attribute in the user profile.
I hope this will point you into the right direction.