A quick update: Methyl Mate is a significantly more viscous liquid than the inject-able cyanocobalamin. This creates two immediate difficulties.
It is very hard to get it into the syringe. Bubbles are much harder to dislodge.
It is more painful to inject, and one must go about 4 X slower than with the fluid designed for injection.
Will observe for any problems with injection site and whether it seems satisfactory in other respects later. As of now, would not particularly recommend using it for injections, though is is possible to do as I outlined above.