That's the best way to learn.

Actually that is exactly what IPMP is for. However there are several ways to use it. In your case you want active-passive, in some scenarios active-active is also used.

You should note however that manual interventions with ifconfig are non-persistent, in addition to the ifconfig, you swap the contents of /etc/hostname.<ifname> files.

Post back if you want the steps for the active-passive IPMP configuration, to do this automagically, or if you'd prefer to have a go yourself then I think it's in the "system administration collection" on http://docs.sun.com