No real "Guide" needed, download this font. http://img.dafont.com/dl/?f=barcode_font
unzip it to any directory on your SDcard (I used the MinimalisticTextPreferences directory that the program uses to store custom widgets you've made)
Long press screen, select "Widget">Minimalistic Text 4x2 (hor) or whatever size you want.
in Minimalistic Text options, to all the way down to Global Settings, scroll to "Font Folder" and select the directory on your SDCard that has the barcode font. press back to go back to the widget setup screen, in the 3 text fields at the top select "Font Family" and you should see Barcode font in the option. once you have it selected for all 3 text fields just make up what you want it to do, clock, battery, date, etc.