He took a good amount of crystals that were stuck to the bottom of a precip jar after all the really big boys had been removed, added some hot water and a cap full of vinegar, and swirled it around until all the spice had been absorbed. He then added a few drops of harmaline extract, and mixed in less than half a teaspoon of COCONUT CREAM.

Use enough 5% vinegar [normal store stuff] to cover and dissolve the freebase dmt, evaporate that.
You can use ~30% HCl acid by sucking some up in an eyedropper and adding just enough to cover the dmt, this will convert it to dmt hcl.
Both DMT HCl and Acetate are going to be oil/goo though, so it might be best to dissolve the product into a saline solution.

Insufflating/Snorting

Preparations to make DMT insuflation more tolerable Snorting nn DMT Snorting DMT works
Hyperspace Fool's COCO Tek For Insufflation Of DMT:

1) Take your dose of DMT and place it in a small shotglass.
2) Mix with enough mildly hot water so that 1 drop will equal 20 mg spice (use more water if needed to dissolve everything).
3) Add a touch of vinegar to convert freebase to acetate (not needed with salt spice).
4) Add a few drops of COCONUT CREAM (not oil, not water)... until solution is cloudy and white.
5) Mix thoroughly and suck it up into an eyedropper.
6) Drop the drops into your nostril while inhaling to spread them over a larger surface of your nasal mucosa.

That's it folks. No burn, and a painless route into deep hyperspace. The end product should be like 10-15 mg per drop. Make it too watery and you will have too much drip. Using a nasal spray with a fine atomizing effect is nice, but not necessary, and for small amounts of solution, maybe impractical.

The longer duration than vaped spice makes this a rather attractive ROA.

NOTE: You can go ahead and add harmalas to this tek if you want to potentiate the spice further... longer effect and less DMT required. Be warned that with enough harmalas, insufflated spice can last a long time and be more like Aya than anything else. And, of course, using this technique when already up on orally administered harmalas is fantastic.

2nd NOTE: Actual amounts and precise measurements have been avoided on purpose because this is a very flexible ROA. Given that some people only need 15mg to get effects and others require well over 100mg, and the fact that most people prefer slightly different ratios here... it makes no sense to be overly specific. Harmalas make a big difference in dosage as well. If you used vinegar, than you might want a bit more cream as well, for instance. Don't worry if it doesn't make sense to you at first. You really can't mess up with this. Just make sure you fully dissolve the spice, and cream to taste. If your drops wind up being only 5mg per drop... don't worry. The drip isn't really that bad, tbh, and you can always lean your head off of a mattress or couch to keep the solution in your nasal cavities for a while.

Hyperspace Fool's COCO Tek method sounds nice

Any tips for masking or better neutralizing the vinegar smell?

you mean ascorbic acid?

if you preconvert the dmt to acetate w/ vinegar, then evap the vinegar, and use it for the coco tek, i am sure the vinegar smell would be minimal.