I'm not certain just how it would work on your scanner, RH,
but I use the scanner lid as a "weight", but insert a pencil between the lid and the bed so the pressure is minimized to only ¼" or less. I have an 11"x17" scanner with the hinge along the back (long edge). When laying the comic open (picture Geo's scanner with a half-sized comic rotated 90 degrees), the lid would come down from the left of picture and the pencil would be inserted right at the spine of the comic. Sometimes I have to use two pencils, one on each side, but usually the one keeps just a soft pressure on the spine and doesn't do any harm. Or, you can use something thicker than a pencil as the situation requires.
Some books, of course, are even too fragile for that, and, like Geo, I either lay a piece of white paper over them and hold them manually or I don't scan them. The ½" of discoloration CAN be fixed in Photoshop using a levels adjustment layer with a clipped-to-layer gradient mask. That's just one way. I often mirror the page border from the clean side and meld it with the darkened side and use gradient mask to blend them. I've never used Corel Photo Paint, so I have no suggestions for that product.
And I simply have no clue as to why people get fixated on the color of the paper. When you think of how many years comic fans DREAMED of getting their comics printed on good white paper instead of pulp... And now everybody is longing for the "good old days" of yellowed backgrounds. Sigh. Comics are almost dead because of the cost. Getting them onto bright white paper has put their price range so high that they've become a luxury item. How come I don't hear anyone complaining about the paper on modern comics? Guys? Why is it okay for new stuff and yet not for scans and reprints of the old stuff? Sorry, but they are SUPPOSED to bright, garishly colored pictures - just read all of the parental and sociological complaints from the '40s and '50s.
I know, I'm just a an old fart and I'm never going to understand this.
Peace, Jim (|:{>