I think the closest match to what you are after is called Sticky Keys.
To enable sticky keys, tap the shift key on your keyboard 5 times in quick succession. This will give you a prompt which (depending on your version of Windows) should look similar to this: 
When sticky keys is enabled, you will see a small icon appear in your system tray that looks like this: 
If you press Shift, alt, control, windows or altGr once, the key will be held down until the next non shift-alt-ctrl-altgr key is pressed (eg a letter or number).
If you press Shift, alt, control, windows or altGr twice, it will stay pressed down permanently.
If you press the Shift, alt, control, windows or altGr key a third time, the key will be released.
You can see which keys are currentyly stuck by looking at the task bar icon. The top white box represents the shift key. The 3 underneath represent (left to right) Control, Windows, Alt (the same as they look at the left hand side of a standard keyboard)