My memory may betray me, but as far as I remember, X-COM medikit did have it own screen with all options and parts of the body wounded. UFO extraterrestrials copied that too. Pretty cool. But a soldier could NOT target himself. No aiming either. It would treat the soldier (if any present) on the imediate (adjacent square) direction the soldier with medikit was facing. TU usage was also diferent. "using" the item wold open the medikit screen and use no TUs. But each time u attemped some treatment (either healing, painkiller or stimulant) some TUs would be used.
A badly stunned wounded soldier would take 2 or 3 turns to "fix":
one MK usage for each fatal wound point healed;
one MK usage for each 10 morale points recovered (lost when wounded);
one MK usage for each 10 points of stun damage "healed" (randomly reveived when hit by aliens or friendly fire).
Note that there was no healing other than fatal wounds healing (would grant some small hp heal with it) so could never be used to get soldier to full health (usually he would be still badly wounded and under heavy stats loss after healing).
That would really only prevent the death of that soldier due to bleeding and prevent him from going mad in panic, never get him back into good shape for action in that same mission. And would waste a lot of the "medic" soldier's time. Pretty realistic.
That would take a LOT of work to code. lol
But would be very cool...