Certificate Authority across forests question

Hi,

I am working on getting my certificate authority to work across forests.

At the moment, it is in "Forest A".

"Forest B" has a number of Sharepoint servers, which for Sharepoint-specific implementation details, require an internal CA.

Is it the right design to enable trust across the DCs to provide certificates to machines in Forest B? Or is there another way to achieve this without creating a trust. In effect, I would like to add a certificate to the "personal" store for the computer account on servers in Forest B.

Thanks