[Zope-CMF] Easiest way to make my own portal_type that is like CMFDocument but with extra properties

[Lynn Walton]

Can someone advise me on what the easiest way would be to create
my own portal product that is like CMFDocument but with extra properties
?

I've read the beehive CMF chapter that shows how to alter an existing
one (main idea copied below to show what I'm referring to...)  ... but
not sure if/how using that way I'd add my own properties.

-----------
>From ZWACKChap5.html
There are a couple of ways to create a new type depending on what kind
of type you want to create. If you want to create a type that is only
slightly different than one that already exists, e.g. if you want to
change the name and representation of a type, you base your new type on
the existing one.

Using an Existing Type to Create a New One

In this section, we will create a new portal type called CV which will
be based on the Document type. The CV type will have its own icon and
its representation will be slightly different than that of the Document
type.
-------------

And I've done the PortalPollTutorial, where I can see how to add
properties but I'm not sure if that's necessary when all I really want
is for my new Document type to be just like CMFDocument but with 3
additional properties.

TIA,
Lynn