IP routing

We have two NT servers runing IIS and being used as web servers. One is a test box the other is the production box. Both have two network cards. The test box has a connection to the private network via NIC 1 and a link to the production box prod NIC2 via test NIC 2. The production box is connected to the internet via NIC 1 . We use the test box to update the prod box, test NIC 2 to prod NIC 2, but want to restrict access from the prod box via prod NIC 2 to test NIC 2.
can I use routing on theProd box to restrict this and will it cause probles if the updates cannot acknowledge completion.