Hi rafix,
Do you have any particular graphic display in mind ?. I mean any particular controller.
Since you don't want to use an alphanumeric display,as you probably knew, graphical display allows you to print different characters size. Thus the ASCII character bitmap depends on your character size and how many pixels you reserve for that. The format for a compiler as 0x34, 0x22... as mentioned by you, it's direct related to the size of your character, thus it can't not be general defined.
Because you're going to use a graphical display, bear in mind that the most suitable procedure it's to build up a bitmap image of the character you want to print and convert this into hex map.
Like this example:
**broken link removed**
Regards,
Silvio