I have the same problem.  I have a few bottles with no wires so what I do
is I hold the bottles to the cage with mini bungie cords.  I use 2 per
bottle, just stretch them across the bottle and attach to the cage on
either side as far as the cord will stretch and it works great.  The bottle
doesn't fall or lean to one side it stays straight.  You can get mini
bungies at K-mart, Wal-mart or the like and they are inexpensive.
 
Kathy and the Krew
Merlin
Cosmo
Katie
Simba
Kazmir Alexander
[Posted in FML issue 3147]