What are the proper straps to strap down your yak?

Hey all,

New to this, but am getting geared up. I just acquired a rack-it style lumber rack with round bars to fit over a 2000 tacoma, so I'm wondering what is the proper way to secure your kayak to the rack, what types of straps do I need and how do I rig them. Any help or pic links would be appreciated. I also saw this on Ebay...it's a shoulder strap that goes through your scupper holes. I like the idea of this for short distances like down my stairs into storage areas...I have to navigate a corner on the stairs that might make a cart difficult so I'll have to huff it. Here's the link...
http://cgi.ebay.com/Kayak-Carrier-Kayak-Sling_W0QQitemZ180278261418QQihZ008QQcategoryZ87089QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Question is, I've heard the scupper holes are weak so maybe devise a strap with a double loop to fit around the bow and stern areas would be better?