With Pete's plugins all you have to do is press F8 while in game, just as fivefeet8 said. For Lewpy's plugin, I'm not sure if the same prcedure will work. If it doesn't, you can alway press "print screen" like slicknick123 advised. Best of luck.
Actually if you just press print screen then the pic will be saved to your clipboard. You have to open an image editer and paste the pic, then save it with the desired name. If you press print screen twice in a row you will only be able to paste the last pic because it will overwright the first one. Pressing F8 however saves them individually for you so you can just hit it a bunch of times in a row and get all the pics.