This is why I didn't get the Veritas honing guide when shopping for one. While I'm sure it's very well made I had concerns about keeping the plane iron or chisel square. Instead, I bought myself a cheaper (around $12) and simpler honing guide. You can find it in several WWing catalogs. It's silver in color and clamps the chisel or plane iron on the sides which keeps the edge square. Works great for me. After establishing an approximately correct angle I'll clamp the blade and mark the top with a marker for future reference when rehoning. Make sure after you're done using the honing guide to dry it off and lube it a little so the wheel and screw don't freeze up from rust.
Layne