Update Word document fields hosted in sharepoint

Hi,

I need to update word document field during an approval.

here is my current project:

We have an intranet application that is used to manage our workflow.
When a process is started, K2 will create a new blank document in sharepoint.
This document contains some fields like 'CreationDate', 'AgencyName', 'ProductName', 'ProductManagerComment'...

During tha process, 5 users should approve the document and add some data : Approver1 should add the 'AgencyName' and 'ProductName', Approver2 adds the 'ProductManagerComment', ...

All User input are stored in the Process Datafields or in the activities datafields.

My question is :
How can I put all DataFieldsValue into the word documents fields? (e.g. for document printing)

Could anyone help me or provider where to find this info.

Thanks