The short answer is that you can’t do it, not really. The best you can do is provide a URL in the compound properties

and then right-click the compound and click Open Netview on URL.

For ICE compounds, a CompoundNode property is loaded into the PPG when you inspect the compound.

This CompoundNode is like a proxy container for the actual compound, and it takes care of populating the PPG with the required controls, and finding the right help page. To do that, it just takes the name of the compound and constructs a URL like http://download.autodesk.com/global/docs/softimage2014/en_us/userguide/files/iceref_MyCompound.htm. (Hmm, having just said that, I figure if you had a local version of the help, then you could stick your own help page there, and Softimage would find it.)

For shader compounds it’s a little better, because you can put something like this in your PPG Logic, and it will work.

#ppg logic start
from win32com.client import constants

def OnInit():
    Application.LogMessage( "OnInit" )
    PPG.PPGLayout.SetAttribute( constants.siUIHelpFile, "http://lmgtfy.ca" )
#ppg logic end

hat tip: everybody on this thread