The easiest thing to do is using junction or symbolic links.
Check command mklink
In Nexus folder where you have the original VirtualInstall folder :
Example for me with Fallout 4
I:\Nexus Mod Manager\Fallout4\Mods\VirtualInstall
Delete the VirtualInstall (if you have nothing in it, in that case move it the new location for example the Z drive)
Then create the junction :
mklink /j VirtualInstall "Z:\Fallout 4\VirtualInstall"
By the way I still do not understand the goal of virtualinstall...