The only way I am guessing here is to use animations. You can set the health for each enemy. Then, have a health bar, so when they take damage, you remove some health from the bar. That's probably your best work around. You just need to play around with the animations until it matches up with the damage.
You can also use several enemies on top of each other. For example: Put 4 enemies on top of each other. The only thing that differs visually speaking is the graphics for the health-bar. Enemy 1 has a full health-bar, enemy 2 has 3/4, enemy 3 1/2, etc. Then give enemy 1 a health value of 1, enemy 2 a health value of 2, enemy 3 a health value of 3 and so on. So when you shoot the enemy (or what every you do to kill them, the first enemy gets killed right away and the second enemy appears underneath with only one life left. Shoot it again and the second will be killed making appear the third one and so on. Use a special death animation on the last enemy in the row to finish him up.
