Custom address with Google Apps

[#1]

I have just signed up for Google Apps to run my email through and I have managed to set the mail up for it by changing the MX records.
I have decided I may as well try some of the other features included.  One thing you can do is customise the addresses of the features to fit your domain (e.g. mail.domainname.co.uk).  However the instructions provided by google don't seem to fit the CNAME settings with plusnet.  Here are google's instructions:
To use the custom URL mail.domainname.uk, you must change the CNAME record with your domain host.
  1.  Sign in to your domain hosting service.
  2.  Navigate to your DNS Management page. The location and name of this page will vary by host, but can generally be found in Domain Management or Advanced Settings.
  3.  Find the CNAME settings and enter the following as the CNAME value or alias: mail
  4.  Set the CNAME destination to the following address: ghs.google.com
  5.  Save changes with your domain host and click "I have completed these steps" below.
From reading the support on plusnet, it seems I may need to do something with the 'A' settings too.
Can anyone help?
Thanks.

[#2]

In this case what you need to enter is the following.
Left field: mail
Type: CNAME
Pri: leave blank
Right field: ghs.google.com (note the ending dot, this is important)

[#3]

Quote from: P

Right field: ghs.google.com (note the ending dot, this is important)

Phil - your example doesn't have a trailing dot.
Shouldn't it say;
Right field: ghs.google.com.
?

[#4]

Aaahhh.... the all important dot at the end.
Sorted.  Thanks!

[#5]

Oops, indeed, though I'm sure you got the point