Read/convert files from a Sony Hi-MD recorder

Got some files from a customer that was recorded using a Sony Hi-MD Walkman MZ-RH10 (Why, you may ask...?!). Ok, just re-record direct from the headset out is possible, but not optimal. So I got these proprietary ***.HMA files (only one of them is large, so I guess it's a package system) that I would like to read - or at least be able to convert to a more known file format. A PC app called SonicStage are used to manage this recorders content, but it's PC only. Anyone that know about a Mac/.HMA converter???