If this is a work system (you didn't really say) then you need to keep your usage work related. If there is software you need to have installed in order to do your job, approach your Admin. MOST admins are very reasonable and will do what they can to make sure you have what you NEED.
If this is not work related software on a work system, shame on you.
If this is a personal system that belongs to a friend or roommate, the best bet is to look at a Barebones system. Get a whole computer for about $300, depending on your needs.
Admins are here to HELP you do your job, and protect the company assests. Try taking the admin out for coffee and explain what you want and why.
NEVER try to get access to a computer that is not your own, and never ask working professionals how to do something illegal.
Good luck.