I took your upload and ported the component to Lazarus trunk/fpc 3.0; VirtualTreeView on my system is version 4.8 of lazarus-ccr (virtualtreeview-new/branckes/4.8 ). There were a few changes related to duplicate names of properties and procedure parameters, the var widestring-string issue, etc. There's one thing which I commented because I cannot resolve it at the moment (unknown EditHandle in procedure TVTPropertyCombo.CreateWnd) - this could cause some issues with a combobox editor, but should not affect the general functionality.
I packed everything into a new package, laz_virtualpropertytree. It does compile and install, but I cannot test it because I don't know how to apply it.
Expect some issues when using my package with a more recent VTV version.