Customizing SharePoint Approval workflow forms using InfoPath

I am customizing a SharePoint approval workflow. The InfoPath Task form needs to be customized to show some more fields from the List item being approved. Example: if approving a list item that has a vacation request, i will need the customized InfoPath form to show fields like (start date, end date, employee name, etc.) as well as a link to view the entire list item being approved. I will basically need as deliverables: 1) the customized InfoPath form 2) a walkthrough document explaining the details how this was done.