this is a trick i use with rue (i have not tasted the flesh of my cacti yet, but i can only assume rue is equally foul - seriously that stuff tastes like mummy vomit):
well first you must understand that taste primarily occurs in your olfactory receptors (Which is to say, your nose), though tastebuds can still detect some bitterness in the conction, it is drastically reduced when not in combination with the olfactory receptors.
as you swallow there is a back-draft of air, just about saturated with vapor from whatever you are swallowing. this makes its' way into your nasal cavity, where it then agonizes (i guess that is the proper term for it? they are
neurons, apparently) your olfactory receptors, forming an unbearable taste.
so the trick, then, is to exhale entirely before taking a sip (or bite, or whatever), then slowly and steadily inhale through the nose for the entire duration (and after) of the swallow. don't forget to always inhale through the nose and exhale through the mouth.
if you exhale through your nose again a couple breaths later, you might accidently gag yourself (i did, lol).
it also helps to have some fragrance for you to smell to cover up any odor of the conction.
and don't sniff the stuff either, as that can cause you to gag.
also when i used water as a chaser, i forgot (or rather, didn't think to) to inhale through my nose as i swallowed i got a horrid taste just from the water.
but using this method i have boldly (yet mindfully) gulped down many brews with next to no taste, that were previously unbearable (to me, at least).
plus it almost acts as a meditative breathing exercise, which is cool too.
freezing, as you mentioned, would probably also help, as i think it would minimize the amount of odorized vapor.
My wind instrument is the bong
CHANGA IN THE BONGA!
樹