I suggest you to use HQ Card Maker. I believe it’s the easiest way to do it.
At first take your image and throw it in the “cards” folder. It can be whatever format you want (jpg, png, bmp, etc)
After that open the “HeroQuest Card Text.xls” and add a new “sheet”. Copy-paste one “card” from another sheet, and change the “back image” with the filename of your image.
Run the program “HQ Card Maker.exe” and choose at the “Package” option your new sheet. Choose the “paper size” you want, the “card size” (in mm or in), the “resolution” you want (as many dpi that bigger will be your image), and choose “Pages” 1, “Back Page”, and no “Round Corners”.
Then press “To File” button and you will have the image you want ready to print on the dimensions you choose.
You can do this for many separated images, and without changing the size of the main image, you can copy-paste as many images (of the same dpi) you can fit in the same image.
Try to do it and you’ll see how easy it is.
ps: I will make it as add-on when I find the time to do it.
the link to download the program:
http://www.yeoldeinn.com/hqforum/viewtopic.php?f=165&t=1059&start=40#p13378