He wanted to transform Image to ResourceLocation, which is not possible. ResourceLocation is just reference, "path", to resource with modid and internal path. What he needed to use, you said above...
No. It is actually possible. Think about skin, it is also from URL!
So, Look into the class 'DynamicTexture'. It will give you a hint.
+ This thread will also help you: http://www.minecraftforge.net/forum/index.php/topic,25161.msg127886.html#msg127886