Which led's do you want to check? If it's the power and reset you need a board,If it's led's that decorate the case they should have a 4 pin molex connector,Connect the molex to the psu and like said earlier connect the green and black wire's with a paper clip or similar and it will power up and look all pretty
You'll have no problem's hooking up the fan's to test them,As for the led's do they have a 4 pin molex connector? if so you can test those with no problem's too.
Yeah they do have the connector. I dunno if I wanna try it though, sounds easy but also sounds easy for me to screw something up, I should probably just wait for my mobo and try to be patient. hah.