You should have a userform in the template into which the user enters that
information and then code in the userform can be used to populate those
properties and place the information in the relevant places in the document
itself.

See the article "How to create a Userform" at:

http://word.mvps.org/FAQs/Userforms/CreateAUserForm.htm

A solution using fields is possible for the Title, Subject, Author, Keywords
and Comments properties, but not the others, so I think you will have to go
along the lines suggested by Doug. But FYI

if you use

{ TITLE "my title" }

or

{ INFO TITLE "my title" }

and select and execute the field, "my title" wil lbe placed in the built-in
Title property. So you can for example use

{ TITLE "{ FILLIN "my title" }" }

Where all the {} are the special field code braces you can insert using
ctrl-F9.

When you execute the nested fields you should see the FILLIN prompt, and
what you enter (with some constraints) should be displayed in the document
and used to update the Properties box.

Unfortunately, this only works for Title, Subject, Author, Keywords and
Comments,and not for the Manager, Company, and Category properties. You
could create a custom property called Manager and link it to the document,
but the result will not appear in the built-in properties dialog and using
the same name for a custom property as a built-in property may have some
adverse consequences (I don't know). If you don't absoultely have to use the
built-in properties, you could consider using links - personally, I'd play
safe and use slightly different names if I used that approach.