How about you learn how to gain some speed and then throw the nade, practice on bombsaway.bsp, once you can hit the back wall at the very top with a nade to the opposite side you can throw a nade as good as any weapon in the game would probably be able to.
Also, I request a REAL LIFE paintgrenade cannon, please deliver it to my house with some ammo, new neighbor's lights are really ticking me off at night.