Lethal Enforcers it's actually not playable in Mame. Le2 it is, but there's a reload bug, in fact you can't reload, only with cheats you can pass through this problem. Also that game don't clearly point where you shoot, so it's a hard task. Others like Operation Wolf are easier to play because of that.
You can play with your keyboard , joystick or even a lightgun (yes, but you have to buy a PC monitor one) if enabled or mouse if so. Options -> default game options -> Controllers tab -> check "joystick", "mouse", etc.
Furthermore, while playing, enter the in game menu (tab key), you can adjust the analog settings there. Test the autocenter, analog speed, etc.
Enjoy
As a side note, can you please make a more self explanatory thread names? That sure would help