How to write %_md5audio% to tags?

Hello Florian.

A special variable %_md5audio% could be used successfully while exporting data. It works instantly for FLAC and fast enough for MP3.

But instead of exporting I want to write audio hash to some special tag of MP3's. Can we have %_md5audio% working in Actions also? Or a tool function writing value of %_md5audio% to a special tag?

UPD. As I just understood %_md5audio% works for both FLAC and MP3 while exporting. Within the actions the FLAC is only supported. My idea is to support MP3 there too.

Windows 7, mp3tag 2.52