The key to getting rid of any insect infestation is the treat the entire plant with an effective pesticide several times at regular intervals.
Mealies, for the most part, I find easy to deal with.
1) Don't dilute the alcohol. 70% is more effective than anything diluted, and won't hurt the plant. If you add a half teaspoon of liquid dishwashing soap (Joy, Dawn, etc.) to a pint of the alcohol, it's even better.
2) When you spray, treat EVERY surface of the plant, and let it sit there until dry.
3) Repeat that treatment weekly for 3 applications. (I sometimes repeat sooner if I see another before the week)
That should take care of it.
If, on the other hand, you have a plant that has the root system colonized with them - detectable if the treatment above appears to be insufficient - then you'll need to pull out the "big guns" and drench/soak the entire plant with a commercial insecticide, agains at weekly intervals, repeated three times.