You have the ability to use the degrees Kelvin WB setting on your 20D.
I use it a lot. Trouble is - unless you have a meter to read - you have to use the old brain/eye to estimate the rating.
I use bright [email protected]
Bright [email protected]
But you will have to mess around with it. Funny thing is thhat a LOT of people don't even know what Kelvin temperature is.
Also keep in mind if you move from sun to shade K temp changes drastically. Kick it back to AWB which is pretty darned good most of the time.
Let me know what you find out with your camera.