Most people consume omega-6's already. They are in just about everything. Soybean oil, sunflower, etc. They are in your Jevity as the fat portion. Jevity 1.5 has just about 30% of calories comprised of fat.

The suggested ratios of 3:6 are 1:1 to 1:5. Very few Americans get that high a ratio of Omega-3. Dr. Wallace's suggestion of 1:3 is in that ballpark. I don't think you can alter your specific diet like a person who is not on a tube. You have a fixed intake of a commercial product. Just do the best you can. In comparison, tests on children with ADHD found that their ratio of 3 to 6 was about 1:25 ! It has been estimated that 1:25 occurs in many Americans as a result.
Start with a fair dose of the flax oil, and work up if you choose.
People do improve on other ratios, anyway. (the Jevity has some Canola oil in it, which does provide a small amount of Alpha Linolenic Acid (Omega-3). The corn oil is all omega-6 and part of the Canola is Omega-6.