You can find related materials under the ispVM installation directory, please refer to following web-page to find the latest version of ispVM:
http://www.latticesemi.com/Support/SoftwareArchive.aspx
The documents to look at are: \ispvmsystem\documents\application notes\ispVM Embedded.pdf
and
\ispvmsystem\documents\application notes\ispVME_AC_DC_app.pdf.
The source code can be found at:
\ispvmsystem\ispVMEmbedded\SourceCode\src\ispvme