Ans could be used instead (I prefer to use Ans so as not to disturb other variables).
Do you mean like using 97 to store a lowercase "a" in a string?
In that case, it could be done, but the program might be a few hundred bytes. I have made several programs that convert a string into ASCII (so that lowercase letters use 1 byte) and I have made a program to convert a string of ASCII into the stuff a person can read. It wouldn't be too hard to make it use a number instead of a string.
Also, do you have an end product in mind? I have made programs in the past the deal with converting back and forth between ASCII and tokens and numbers for various reasons If you can give an idea, that would make it easy.
A friend of mine was working on a text editor a few months ago, so I made some programs that used ASCII so that each char used 1 byte. One was designed to take the ASCII data in a string and output it as chars. Is this what you want? I have the programs still.