I haven't used these but a straw or coffee stirrer inserted in the cake and then the wire in the straw should do the trick. Otherwise, take a look at the angles of insertion.
you could coat them in chocolate too. or use a piece of fondant or modeling chocolate at the insertion point (just smooth over with b/c if that's what you're covering the cake with. and you can bend and insert the part going into the cake at the opposite angle of the direction they hang to sort of cantilever the weight.
Thank you, thank you, thank you, Deah and Jen!!!!