Comment by DaCapoo

Control isn't necessary - I'm not sure why it would be specified. On a laptop you might have to hold the Fn key to hit PrtScr, but aside from that it's two fingers to hit 'Right Alt' and 'PrtScr' and the other hand can mash r,e,i,s,u,b.

Source: http://en.wikipedia.org/wiki/Magic_SysRq_key