I would recommend using cdnshelp to look at the documentation. You can edit the preferences to add multiple libraries of documentation (e.g. from different Cadence streams, e.g. IC, PVE, INCISIV, MMSIM, etc) and then can search across all of them. It's got hyperlinks, an index which makes it easy to find the right manual, and you can open the manuals in pdf from here if you want the published formatting.
In general searching via google wouldn't find you the documentation, because any documentation that is found this way is only likely to be there as a result of somebody violating their license agreement which disallows re-publication of our material. So usually you'll only find really old stuff where nobody has bothered to ask them to take it down.
The other alternative is to look at the manuals on http://support.cadence.com . I personally prefer cdnshelp, but some people use the Cadence Online Support route all the time.