If the IT guy of said library knows his job you won't be able to mine anyways, because he'll have blocked any ports except for HTTP, HTTPS and maybe the most common ports for Mail.
My advise: Just forget mining if you want to do it to "earn" money. Either safe up some Dollars and then just buy Bitcoins directly and do some trading (buy low, sell high) or do stuff that get's paid in Bitcoin, like a Signature Campaign in this forum.
He won't be using their Internet anyway, so I doubt the IT guy can do anything about it.
Oh I kinda misunderstood that part. Well if he's going to use mobile internet and the mobile internet package he is paying anyways isn't enough and forces him to upgrade it just for mining then that upgrade's price will eat up his income from the mining considering that he wants to use small miners like the Antminers.