This can be done EASY 
if(GetAsyncKeyState (VK_NUMPAD1))
if( GetAsyncKeyState(VK_SPACE)<0)
PushToConsole("PlayerGravity 800");
else
PushToConsole("PlayerGravity -800");

if(GetAsyncKeyState (VK_NUMPAD1))
if( GetAsyncKeyState(VK_SPACE)<0)
PushToConsole("PlayerGravity 800");
else
PushToConsole("PlayerGravity -800");


