HOWTO reduce downtime for upgrade of R12

Hi,

I'm after anyone who can share their experience of using note 734025.1, Using a Staged Application System (APPL_TOP) to reduce patching downtime in E-Business Suite Release 12.

I would like to have a go at using thismethod of reducing downtime but am having difficulty with a number of points;

"Production and Staged systems should have the same APPL_TOP names", Where would one set this?  

"You must have different Applications system names for Staged and Production systems", again how and where is this set?