The classical way of making HCl salts of drugs is by dissolving the freebase in a dry nonpolar solvent and gassing it with dry HCl gas (made from e.g. sulfuric acid + hydrochloric acid). This is kind of dangerous if you don't know what you're doing, dry HCl will rust metal surfaces away very quickly and will also do terrible things to your skin and tissue.
I bet a FASA tek (fumaric acid saturated acetone) could be adapted to work for 4-AcO. There's no reason it shouldn't. To ensure you get a good yield avoid heating the product too much and strive to use dry acetone where possible. (Dry it over anhydrous calcium sulfate (Drie-Rite, plaster of paris) or magnesium sulfate (Epsom salt)). One could also use maleate, malate, lactate, citrate...