First open the Script Editor...then in the script editor find Edit menu and choose Edit -> Echo All commands to make sure the script editor will display any command you execute.
Now from viewport's view menu choose any command you want , lets say it is View -> Camera Tools -> Tumble...the script editor updates your tools change and will display something like following string:

setToolTo tumbleContext;

This magic words is what we is what we have been looking for...and finally found...lets not to waste our time and proceed with our maya hot keys exploration my young friend :)

The nexts steps are very simple aspecially for such talanted and capable student as you, dear genazvale!

Go to Window -> Settings/Preferences -> Hotkeys...
Huge dialog box opens...
At the "Key" field type any key you want to use as the hotkey,
press Query button to make sure it wasn't used for any other command...if it was, then try another key or any combination alt or/and control to find unused one. When you got available key,
go to the bottom of dialog box and fill the Name , Description, Category fields( in the Description field don't forget to put my name as a person who help you with this problem and also everything good you think about me (just kidding =)
At the Command field you want to paste the command string you have at the Script Editor..Now press "Assign" and Save button. That's it. thanks please.. :)

Veniko, Genazvale...
Gde spasibo to? Bolshe otvechat' tebe na tvoi voprosi ne budu..chitai manuali..Ne znaju kak v gornoi dalekoi gruzii a u nas ljudi obichno blagodorjat drug druga...