Trust between NT4 domain and W2K domain

I’ve got 2 one-way trust established between my 2000 domain and NT4 domain. Does anyone know how to add users from the NT4 domain into one of the groups in the 2000 domain? Does anyone know if it’s even possible? When you go to add users in the 2000 domain, it just gives you 2 choices, directory and the name of your domain. And all the machines can see each other.