Need advice on timing belt tensioner pulley

[equalizir]

Hi all,
i plan on changing my timing belt on my 2001 xterra soon. Id like install advice on the timing belt tensioner. Ive read on other forums they recommend using a belt tension gauge. They make it sound like theres some special art to getting this thing on right. I was wondering if someone can tell me how to put one of these on? I dont have a gauge to gauge the tension but just from looking at it doesnt seem that it should be difficult to install and do the job right. Thanks in advance.