That's kind of like asking for the recipe to Campbell's chicken noodle soup. If you really like Campbell's then you are setting yourself up for disappointment if you want to make chicken soup from scratch and expect it to taste just like Campbell's. But even though everyone knows the ingredients to Campbell's are salt, water, noodles, salt, chicken and salt they aren't going to give the exact recipe away or else they wouldn't be able to sell the stuff.
Try downloading QBrew. On another message board (I forget which, but it concentrates on Mr. Beer) somebody put together an add-in that will incorporate the different Mr. Beer HME's and UME's into the ingredient list. That will give you an estimate of the gravities and colors of the different Mr. Beer cans and you can go from there to replace with different grains and extracts. That wont take hops into account, but you can get a basic idea of what style of hops are likely in a Mr. Beer can from their descriptions on the website. Then go from there.