Ok, themadhacker is right about the power adaptor... sorta. Be careful about the polarity. Most adaptors should work but some will fry it. According to mmmonkey a Megadrive 1 power adaptor will work, so if you have a Genesis 1/Master System power supply that should work.
Video is a problem. The video signal is PAL 50Hz. Most (but not all) NTSC TVs can use the 50Hz signal, but very few can decode the PAL colour. So basically you will either have a good image (unlikely), a nice black and white image (most likely), or a garbled black and white image of fail (somewhat likely). If you get a garbled picture, look for something called vertical hold, I don't know how it works or what it does but apparently it will fix the image. If you 50/60Hz mod your SNES, you can set it to 60Hz, which should give you a stable image on any NTSC TV. Unfortunately it will still be in the PAL colour format, and it will still be black and white. At this point you can connect it to an RGB-capable display and get full colour, but very few things support RGB in NTSC-land. If you want to use it with your TV, you need to buy a converter. The cheap ones will get you colour, but you still need a TV that gives a stable image or the SNES set to 60Hz. If you can get a stable B&W image without the box the box should give you a colour image. Linky: click here
. That one is from Canada but they ship to the US cheap I think.