You would probably need to create home2 on the other disk, then possibly symlinks in /home pointing to it would work, or else you could put fstab mounts into /home (after clearing it out first -- as with the guides). But I think you'll find that /home generally isn't the culprit for disk consumption. A better consideration would be to put /var/vmail on another disk and mount it at /var/vmail in the filesystem. For instance, I have one packrat customer that has 75GB of mails in /var/vmail. Sum total of /var/vmail on that server is over 200GB of my 300GB disk allotment!
Or did you put /home on a separate partition?