Multiple digital signatures

I am trying to create a document that can be certified as ready for review and signing and then circulated for multiple signatures .

The document( a standard operating procedure ) must reviewed and signed by 5 or 6 people and I have to be able to prove it has not been changed other than being signed but I can't figure out how to make signing the form fields as an allowable action.

Here is what I'm doing now

create document in word and convert it to a pdf in adobe acrobat 8 pro on windows xp
in the form menu click create new form
click through and use the current document to create form
In Live Cycle designer I :
Add the digital signature fields
then I'm lost

This seem the closest to what i want to do but this seems to complicated
http://www.adobe.com/devnet/livecycle/articles/multiple_sigs_tip.html

I don't think I need a policy server but I'm not sure.

I just need to invalidate signatures if someone uses acrobat to edit the document text and images after it has been certified and/or certified and signed.

Thanks

John