Why would need a hack on getting subscribers? Whats the point? Even if you do have thousands of subs but majority of them arent your target audiences then it would be still a useless thing and
as suggested above the best thing to do is hiring a community manager which is more worth or real thing to be done rather on thinking on how to hack or fasten up your subs yet it wont
really give a significant effect on the project that you are planning to promote.