I'm not sure how you mean, I tried entering %A3 and it just entered those characters!!!
I tried using special characters button and it still failed although it looks fine when viewed inside CMS but not when web viewed.
If you can try putting a pound in by keying alt 0163, (gives a £), saving it and it still looks good (£) in the CMS details page. But if you look at the page on the net its changed to Â£ ?????? Chris