Use cheat engine, select correct process.
For Infinite Health:
** Change Dooble to value tipe
5. Fisrt scan Ur Health
6. Close Ur enemy, u'll be be shoot ( dont be dead, or u lose)
7. Next scan ur health ( u must get only 1 address )
8. change value to 9999
9. Done
U never die now

For infinite Ammo:
** Change 4bit for value tipe
5. First scan ur ammo
6. Shoot wherever can shoot
7. Next scan ur ammo
( u must have only 1 address, or shoot something again)
8. Change value to 9999
9. Done
Now... shoot anything, u'll never lose ur ammo
Good Luck, and dont Lose