You may not preserve the enzyme using a decalcifier, and will have
to get into the literature to make sure the acid does not ruin the
enzyme.  A researcher  by the name of Sande Marks, Jr, did some elegant
GMA/enzyme technics.  Ref is Marks, SC Jr et al, Tartrate resistant
acid phosphatase in mononuclear and multinuclear cells during the bone
resorption of tooth eruption.  J Histochem Cytochem, 35:1227-1230, 1987.
He also controlled the polymerization temperature by performing cold
GMA embedding, probably allowed it to polymerize in a refrig, easy to do,
and work on ice block while embedding.   I strongly recommend reading his
work.

If you decalcify, you will need to RINSE the acid out of the tissues
thoroughly or the GMA tends to polymerize poorly, this is particularly
true of if Bouins is used, but that may not be a fixative of choice for
enzyme work anyway and acid decalcification may also be unacceptable due
to enzyme inactivation.

EDTA is a good choice for enzyme preservation, and if used, must be rinsed
out of bone thoroughly.  Our lab did some EDTA decalcifying for GMA, and
the bones cut very well, but had to be very thin slices, no more than
1 - 2 mm thick or GMA will not polymerize well.  alk phos will have
to be restored after EDTA.

Good luck
Gayle Callis