You can either buy lowering springs or you can adapt coilovers from a VW MK1 rabbit. Click on the link below, Petrified Rabbit has a very informative how-to and a list of the things you'll need. He also sells kits to make the coilovers fit our car's.
http://www.aveoforum.com/forum/f85/c...osspost-10551/
I edited this for a more correct rear fitment, the mk2 coil overs work best in front, the mk1 is best in rear, but the mk1 also work in the from so it is best to buy all mk1 suspension.