Noob, I think my friend is trying to do the same thing as you.
Here's how s/he's planning to do it:
1) Basify MHRB w/ NaOH or calcium hydroxide
2) Extract with non-toxic d-limonene
3) Add fumaric acid saturated water to the limonene layer
4) Evaporate the water layer to get DMT fumarate. This could later be freebased with or without the use of naptha. If you are interested in freebasing w/o naptha, do some searches, I think jorkest has a good tek
As for your question about purifying DMT salts with MEK, I don't know (and judging by how nobody has answered it yet, I'd guess they don't really know either).
However, you could probably get high purity DMT fumarate using FASA (fumaric acid saturated acetone). Just add it to the d-limonene layer (i.e. change step 3 to "Add fumaric acid saturated acetone to the limonene layer" ). That should precipitate the DMT fumarate right in solution - no need to even mess with MEK! (which, afaik, is considerably more hazardous than acetone).
If you are like my friend though, and want to avoid anything using anything chemicals from the hardware store unless absolutely necessary, you could do her limonene & fumaric acid saturated water technique. This tek ought to yield DMT fumarate of about the same purity as the acetone-based tek.