What type of glue can be used to stick aluminium to plastic?
some glue that will set as rubber


That would be something like Sugru


  Sugru is mouldable glue. Stick it, shape it and it will turn into rubber. 


I don't know whether it will adhere well to aluminium and whatever polymer Apple use for "plastic" feet. However they do say:


  Sugru sticks permanently to lots of stuff like ceramics, glass, metal, wood, and most plastics and fabrics.


(my emphasis)




  The MBP gets hot


According to Sugru: 


  it'll stay strong and securely bonded anywhere from the freezer to a steamy hot shower


Might be worth trying.