NFS

Use the Utilities/Directory Utility application.

Samba

Since netinfo is gone, you'll have to manage the automount maps manually. Here is an article on how to create an automount map specially for Samba shares:

http://www.stress-free.co.nz/automounting_samba_shares_in_leopard

Alternatively, you can use the /etc/fstab. Here's an article on how to do that:

http://www.macosxhints.com/article.php?story=20071028194033157