youre trying to get objects to separate out in a final render? You can always hide the visibility of object and render individually. and if youre talking about rendering out to separate photoshop like layers, Cebas has a plugin called Psd Manager which will separate them.
maybe you could check node render id, give to your objects a different g-buffer id, for example 2 for all glasses, 3 for trees. you render your image, then select from the VFB the object layer and then u can use it as a mask, to separate the tree, glass etc. I mean if you want to post work it.
psd-manager works with Vray! You can create mattes for materials and objects and use them to edit individual parts of the image. Of course you can not add render elements to the PSD file since Vray doensn’t support render elements, but all the other stuff works. Try the demo.