Is there a "How to" that explains how to migrate the sales module (va01, va02, va03) with SAP portal?
I don't understand the question. If you are migrating the portal from say EP6 SP2 to Netweaver, the content that is SD related goes automatically. If you are asking how do I include the SD transactions like VA01 in the portal, there are a number of ways. You could create transaction iviews or use a business package that has the iviews, pages, etc. already created.
Please be more specific what you are looking for.
You can go to this link to see how to create transaction iviews at this link http://help.sap.com/saphelp_nw04/helpdata/en/88/266a3e54a2e946e10000000a114084/content.htm.
You may want to try out some of the business packages on the portal content studio. There is a business package for Sales that I believe they have most of the SD transaction in iview form