Not many PCL printers have resident bar-code fonts, although there are a few that do.
So you will probably have to obtain a suitable PCL format font (for the bar-code symbology you have chosen); this may be provided as either:
hardware (DIMM or equivalent)
software (downloadable PCL-encapsulated format)
Then you would be able to select the font (by ID, or via characteristics; font vendor should provide details).
You may need to add things like stop/start characters, calculate checksum character and maybe even translate characters (if the font characters do not have one-to-one correspondence with actual character codes).