Just to clarify I think it may not send <CR><LF> as actual carriage returns / line feeds I think it will just send '<CR><LF>' as a string. Some clients will automatically convert <LF> for you. I wasn't sure but I looked back at the printing project I did (simple example here Industrial Label Printing with MII? ) and I had to put actual line feeds in the string to get it over the wire right for the printer to understand. The only caveat is that I was using an older versions of MII and an older version of PCo and the functionality had just been released. Anyway good luck and keep us informed of your progress.
Regards,
Christian