How to intitalize data in Program Memory
To put a constant string in data memory you need to use the rom qualifier in C18 compiler:

rom const char[] = "some string";


EDIT: As an advice for future questions you might have regarding the C18 compiler (or any other compiler, for that matter): please read the compiler's manual before asking for help. I haven't used the C18 in a while and I had to look up the information you needed. It only took me 2 minutes to find the manual on the internet and look for the relevant information. I'm talking from experience when I'm saying that it's much more rewarding to find the answers yourself than to ask someone for help, especially when the information is easily available.