That's not the way a text editor (vi or emacs) works or may be I'm not aware.
1. Ok, tell me this: if you want you want to manually change the formatting codes (say, change colour from blue to green) by yourself instead of a perl program doing it, how will you achieve this task?
2. Why do you need to see coloured text in an editor? Rather, you could
familiarise yourself with the formatting codes.
3. What is the exact requirement?