Fitting's not too difficult:
Catch can on battery housing
Fit new breather pipe and o ring
Connect breather pipe to bottom of T piece with 19mm hose, connect suction pump to one side of T piece with 19mm hose, connect other side of T piece to catch can port with 19mm hose (and 15mm hose & downsizer if using 15mm ports on can)
Remove Y pipe and connect TIP to other can port (using 15mm hose and downsizer if using 15 mm ports on can)
You can't go wrong with this guide
http://uk-mkvs.net/forums/t/269734.aspx?PageIndex=1