Rethink your question, then rephrase. It is not clear what you want.
Regular hotkeys all work when you are in text mode, like Ctrl+C or Ctrl+V.
Do you mean the single letter hotkeys for tools? You should be able to go to Edit > Keybaord Shortcuts... and create a custom set, then modify anything you like with the caution that style shortcuts are required to use a modifier and a numpad key, and the numpad keys are reserved for styles.
Yes, sorry I should have explained more clearly.
The problem is that the single letter shortcuts doesn't work when I'm in a textbox (of course, they shouldn't). But still, beeing able to use them through a modifyer key for example would be great.
I will try out your suggestion.