Bardon wasn't speaking against drinking itself there. I'll just quote the whole thing (to save myself time, from the pdf version):
Manage it so that you spend as much time as possible in your rise or advance. It is quite unnecessary to waste time with sitting for hours, drinking beer and passing time in trivial company. Time is running away like water, never to return. A certain amount of time ought to be provided for, but it is very necessary to stick to it. Exceptions ought to be allowed for only in quite inevitable cases. Man is subject to habits, and once accustomed to a definite timetable for his exercises, he will feel compelled to do his exercises. In the same way as there is a want for the necessities of life such as eating, drinking and sleeping, it ought to happen in regard to the exercises which must, as it were, become a habit. This is the sole way to attain a sure and full success. There is no prize without diligence. It is my ambition to arrange for the instructions as if they were meant for the busiest man. He who has plenty of time of hand may be able to be occupied with two or more exercises at the same time.
His emphasis in that whole area was on having a schedule that you stick to when it comes to practicing the exercises, so you can be constantly progressing, not stopping drinking (though of course, if that's what you want to do, then absolutely feel free to). So you set it up and say "I will practice voiding my mind of thoughts at 9pm for 30 minutes every night" etc. Then you stick to that.
As to how to do that, ultimately what it comes down to is just making a firm decision. That is the first step. Many people make a decision without really making a decision. They say "I will start this practice routine"...but they don't give themselves a set time to do it in etc. They always leave an "escape route". The first step is to close the escape route, and make it definite.
After that it is a lot easier, and it just gets easier the more you stick to it - until a point will come when it is harder NOT to.
Then, make sure you know WHY you are doing this, what it gets you (even...no, especially if they are "egoistic" reasons, since that will appeal to your motivation much more) Actually write out reasons why and review them occasionally, even modifying them as they may change over time. Keep a "diary" of your practice, changes over time so you can see progress that was made to help keep you motivated, knowing you ARE progressing.
Initially, when you wake up or before sleeping (or after meditating for a while) you can as vividly as possible just imagine to yourself that you are keeping a habit and doing the exercises. So at night time, you might imagine getting up in the morning, seeing the clock with the time that you have decided to practice, and see yourself sitting down and doing the exercises for however many minutes you decide (and while your at it, see yourself as finding them easy, enjoyable and doing them well). And keep that imagination nice and easy. It really will help the habit form. It doesn't have to be hard.

When you do introspection you can look into reasons why you may NOT practice, what would lead you to avoid it. And delve deeper into why you might do what you do to avoid it - what do you get by doing that which makes it more pleasurable then doing the exercises (or less painful). Analyse it. Look at ways the practices ARE pleasurable, make doing that appear more painful. Look into your beliefs behind why you avoid it, then you can change them into beliefs that encourage your practice more...loads of ways to do that, such as bardon's methods of impregnating drink, food, air...autosuggestion. Affirmations and particularly visualizations work well after meditation (visualization is better if you are NOT doing it to change, but simply to "pretend" for the time that that is how you are) There are really countless effective ways to do it.