3 independent ks files all point to vgrade, that's all I found about plasma+mer:

http://bug10738.openaos.org/images/exopc/mer-plasma/handset-ia32-plasma.ks
http://images.formeego.org/n950/plasma-active/plasmaactive-armv7nhl-n950.ks
http://bug10738.openaos.org/images/tegra2/mer-armv7hl-plasma.ks