Searching for user in multiple forests over a 2 way forest trust.

I have a large enterprise network that has multiple forests (5 forests in total). One of these forests has a 2 way forest trust with the other 4 forests.

I am building a webpage in .net that is required to be able to search for users against all forests. I have a service account created in the forest that has the 2 way trusts with the other 4 forests and have requested that this account be granted read access to be able to search the domains in the other forests but cannot seem to get any search query to work on any of the other forests.

I have spent the last few days trying to research this online and have only seen solutions for searching AD in a single domain in the forest or across multiple domains in the same forest using the global catalogue.

Does anyone know how to perform this kind search or even if this is possible?

This should be possible with a Phantom Root (http://msdn.microsoft.com/en-us/library/aa366988(VS.85).aspx) search. You should get referrals back for the four other forests (which your code will need to chase) in order to complete the full search.