Similar to the Large Medipack method but this time hold your ctrl on the small medkit (remembering to have just one small medikit left)and press 0 to activate the unlimited small medkit.
I recently discovered this cheat and it was good. To have unlimited Large Medkit do this. while on a level make sure you have only one large medkit left. Remember to not use it. try damaging your self a little, either in water or by some guards. after that, go to the inventory were you left the last medikit and do this. Hold down CTRL making sure you don't take your hand off and press 9 together with the held button. The kit will change dramatically. close inventory and head back to it again to see unlimited large medkit.