There's something (without NAT-use) in 2.2.x

Load balancing with 4 ethernet devices (sebastien)
Date: Tue, 30 Mar 1999 08:16:22 GMT
From: Michael Hasenstein <hasenstein@yahoo.com>

ftp://sliepen.warande.net/pub/eql/
It doesn't use NAT so it's different (advantages/limitations) from what I suggested in the NAT paper. Maybe it's something for you.