Assuming you injected the hack correctly, you just need to hold X down and right click an creep. Make sure auto attack is turned off in your Dota 2 settings, as it can mess the feature up.
the injectionproblem only fucks up animationcanceling stuff, which is the orbattackthingy and lasthit.
try using the betaclient, it mostly works flawless.
and make sure that the keys you use in the hack are not binded to something in dota itself.
i personally have unbinded L ingame, set the hack to use L as lasthit hotkey and then rebinded L to a special button on my mouse. just as a tip