I am in the process of working on an override of a customfield plugin (catproduct by SMPlanet).
The plugin is as far as I can understand overridable, and is located in /plugins/vmcustom/
the main plugin folder "catproduct" contains a further folder, also called "catproduct", which contains a number of folders, among which tmpl, containing the template .php file (default.php in this case).
My understanding is that one should copy the folder "catproduct", contained in
Strangely though, Virtuemart does not seem to be reading from the tmpl default.php file in
but only from
e.g it seems Virtuemart is not loading/accessing the customfield override