Running cdnshelp either pointing at your MMSIM installation, or running the cdnshelp that's in your MMSIM installation will do this:
`cds_root spectre`/tools/bin/cdnshelp &
Then you can navigate down to spectre and find the manual. You can search it, follow hyperlinks, and even open the pdf.
You could also just look in the installation under the doc dir, and find spectreuser/spectreuser.pdf . But cdnshelp is intended to get you to the documentation...
You can also bring up Help from within Virtuoso (assuming you're using IC61, which maybe you're not) and add a library to point to the MMSIM docs so that you can get it that way.