No, unfortunately you cannot. You can do a couple of things here. If you go to R1C1 reference style, the columns will be 1, 2, 3, etc. Or, the preferred alternative (imo) is to hide the column headers and make row 1 your header row. Then enter the information across row 1 and format as desired.
Formatting is highly underated. With some good formatting you'd be surprised about the changes and ease of entry it makes for user's. Remember, use KISS - Keep It Simple Stupid.
Not on the actual row & column headings (as far as I know you can only change those from A,B,C... to 1,2,3 etc....), but if you just don't want to use normal headers like the rest of the world, you could sure turn off the row & column headings and make your own out of Forms toolbar buttons. (One for each column). Could be rather tedious, but you'd only have to do it once, they could say anything you want and you'd be the only one on your block to have one like it! (Not to mention you could assign code to them...)