LLBLGen Pro Team
The Hague, The Netherlands
if you specify /D=path
it will override the installation path (but can't contain any quotes). It's an NSIS installer so it uses the same arguments http://nsis.sourceforge.net/nightly/Docs/Chapter4.html#silent
The VSIX installer will run though as you can't uncheck the option when using the silent installer and that install is non-silent. So it's not really supported 100% but you can get a long way.