Presuming MS Windows:
pfid = fopen('LPT:', 'w');
fprint(pfid, 'something to be sent to the printer');
fclose(pfid)
This simple version assumes that the printer will handle printing plain text. Which is perhaps getting increasingly rare. But if the printer will not handle printing plain text, then write the output to a file and then tell a program to convert the file to whatever your printer does handle (e.g., pdf files), and then to send that resulting file to the printer.
If you want to launch the MS Windows printer tool, there is an ActiveX somewhere around that can deal with that.
