I'm not sure what has changed exactly and whether being EU or not makes a difference now but I came here to do a language course and was given an L permit.
I found a job, brought the contract to the authorities and they changed my L (short term student permit due a short term language course) to a B.
I am from the EU though so things may be different if your from the US. As far as I know, if you are a full time student you can work 15hrs a week (I even did more at one point when my employer was very short and nothing was said. I did about 75% on top of my studies for a month or two, was tough but I wanted to please the new boss

)
Your best bet as always is to contact your embassy to find out what your rights would be exactly.