Only thing that has worked for me is "Dubbin" - it's a grease applied to a heated boot (wood stove in camp works just fine) apply until no more will absorb. With a good boot, will keep your submerged feet dry for almost 8 hours of work with a lot of submersion. Snowseal didn't work for me for more than about 2 hours.
The boots lasted for 4 years after this abuse - long enough to afford another pair.
Nowadays, I wear a rubber botton, leather top - North Face boot - comfortable and 100% water proof - dubbin on the leather still works well and I've been wearing these boots for 10 years now - normal hunting and not submerged like when running seismic lines srtraight through the bush.
-------------------- Daryl
"a gun without hammers is like a Spaniel without ears" King George V