Two nice American English ways of saying du kannst mich mal are Fuck you! and Fuck off!, both of which can be used in many, many situations. Another way you could get your point across is Blow me! All three of those expressions are rather vulgar, however. If you are looking for something not as vulgar, perhaps you could go with Stuff it! or Shove it! (as well as Up yours!, which folletto already suggested). Nothing much less vulgar than that comes to mind, but maybe someone else will give you some more suggestions.
Take it easy,