Hi, according to the oracle agent installation instructions you just change
HOST= in the listener.ora and tnsnames.ora to the failover address.

In my /etc/hosts file on both nodes I have an entry for the high availability
ip, this is the same hostname I use for HOST= in listener.ora and tnsnames.ora
on both servers.

When I do this the db and listener start as usual but I can no longer connect
to the db remotely.

The only thing I have to note is that when the listener starts, instead of
showing a hostname it shows my failover IP.

Connecting to the db is then no longer possible by specifiying it's name.
sqlplus SYS/password AS SYSDBA still works from the node on which the db
is installed.