Yes, you can do it with AutoHotKey. I tried it a few years ago but didn't really get on with it. I think it might have caused problems with some keyboard shortcuts I use - a lot of my emacs shortcuts are designed for activation with one hand pressing modifier keys and the letter key.

Anyway, just use the < and > modifiers to indicate left or right Shift specifically. For example, assuming QWERTY:

   <+q::Send q
   >+p::Send p

but wait, this doesn't get at having shift behave normally unless it is the only key that gets pressed. Does it?

No, sorry - the bit from the article that was in my mind as I replied was forcing one to use the opposite Shift, because I'd tried that myself. I didn't think about the use of Shift as a key on its own (I really wouldn't get on with that myself as I tap the meta keys a lot while I'm thinking).

create a file, ctrl-to-esc.ahk:

  Ctrl::
  Send {esc}
  Return

Then run the script and AutoHotkey will sit in the background, waiting to substitute a lone ctrl for an escape-key-press.

I haven't figured out the shift-parens yet, unfortunately.