Every routing protocol support equal cost paths load balance but by default EIGRP can be able load balance between four unequal paths (those paths should be feasible successor routes) so you can be able to add them to routing table by variance command.
for instance if you have route with feasible distance (FD) 500 and two feasible successor routes with FD:1400 and FD:1600 then you should choose four for variance :
4*500 = 2000 (1400 < 2000 and 1600 < 2000)
but if there is another feasible successor with FD:2100, it doen't add to routing table with variance four, because 2100 > 2000
then router divides traffic between three paths :
FD:500 1600/500 = 3 packets
FD:1400 1600/1400 = 1 packets
FD:1600 1600/1600 = 1 packets
for more information :
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009437d.shtml
