98 Silhouette engine removal/rotation

I am trying to find information on how to rotate the engine for my van. My husband need to replace the first emission sensor and any instructions that we find say "rotate the engine" in order to get to the sensor. He is pretty handy and it was suggested that we try replaceing the sensor prior to replaceing the entire catalytic converter. We need something a little more specific than "rotate". Any help or ideas would be appreciated. Thanks!

Try this link from the Venture forum (sister to the Silhouette) on moving the engine forward:http://www.automotiveforums.com/vbulletin/showthread.php?t=521860
From the Montana ( another sister van) forum:http://www.automotiveforums.com/vbulletin/showthread.php?t=756459

what emmisions sensor? are you talking about the o2 sensor? if so you do not need to move or rotate the engine..