Is it possible to add a Hotkey to an action that I added myself?
No, unfortunately not.
really need this feature...
especially for web sources scripts...
tired of clicking 100500 times..
thanks in advance!
You can add the characters & and # to the names of action groups and to the .src files of the Web Sources to make them available for navigation with the keyboard.
Alt + A to access the actions menu, Alt + S to access the web sources menu (if you are using Mp3tag in English).
Thanks for the tip, but it's not really giving much performance when tagging 100x+ releases 
Really need something like alt+5 but for specific web sources scripts, don't think it's hard to build into mp3tag. (actually just bind custom key presets for menu actions)
I would like that too. Would be nice.
Another tip:
Alt + Ctrl + I always calls the last used web sources script and skips the search field (like the Quick Web Souces button), so that can be another time saver if you always work with the same script.
Yes, but the problem is I rarely use the same search field data, because I'm tagging different releases.