i never did it by myself but there is a way to check why there is a squeak on the belt and actually most of the time belt is not the reason..
spray some water on the inner side of the belt while engine is running of course.. if you start to hear squeaking higher it has to be a tension issue.. if squeak wont get higher, take out the belt and turn the pulley bearings should turn pretty smooth without any noise and any slack (a bit is ok).. a small slack can cause the noise also..
if its a tension issue after adjusting it to factory setting dont forget the run the engine for at least 5 mins and check it again.. so tension adjusting needs to be done twice not once.. if there is still a sound, tensioner pulley needs to be changed and tension shouldnt stay the same of course after few seconds.. better go for OEM belt also.. it should help you out.. and if there is still some noise turn off the engine and run away from that car..
