First, they will NOT be happy if they catch you doing this... i wouldn't be surprised if they fired you for it (so is it really worth it?).
oh, and your actions are your own. information supplied as examples, not tutorials to be followed :P
Content filtering can work in 2 different ways,
a) There is a list of websites that you are not allowed to see such as addictinggames.com, youtube.com, myspace.com etc (a blacklist, anything on the list is blocked)
b) There is a list of website that you are allowed to see such as boringcompanywebsite.com and other websites you need to do your job (a whitelist, anything not on the list is blocked).
Type (a) is very easy to get around, type (b) can be a lot harder if not impossible... from your description it sounds like type (b) but i want to make sure.
How is your internet access censored? is it software running on the computer you use or a computer on the network?