Peugeot 306 1998 TD Auxillary Belt Tensioner

Hi, Recently had the cambelt changed on my 306 TD 1998 (air con version) and mechanic noticed that I needed a new tension for the auxillary belt as it is off alignment. I didn`t have the part at the time (doh!) so don`t want to fork out for labour again (don`t like doing cam belts anyway ;-).The tensioner wheel is the one that sits higher than the "adjustable" other wheel. Now, question is , access is very limited so how do I get to remove this wheel and replace it with my nice new =A372 one (!). Is it best to remove the engine mounting and "drop" the engine down so I can see the wheel more easily (after removing wheel and inner shield)? How do I achieve this? How does the old tensioner wheel come off? Is it clockwise turn to remove it? Any advice, greatly appreciated. I`m going to tackle this on my own!! Thanks