from what i could tell from reading vray docs and looking at vray assets from cosmos, the idea is that you could also go through the bitmaps > convert them to vraybitmaps > then set the color space transfer funtion & further down, RGB primaries to sRGB & sRGB primaries.
now, for forest objects i was using the built in vray converter bitmap to vraybitmap.
for my last playing around with it, the colors aren't going to be super exact render-to-render, but it's pretty close to the old gamma workflow.
the other thing is, in the 3ds max color management settings i set my displays and views like the attached image. this gives me the benefit of saving out a 16bit tif file from the vray frame buffer. so you get not only the wider color gamut, but also greater bit-depth in the image which is the best way to capture and work with all the colors you can.
in the vray frame buffer, when you are going to save, make sure include the option to save the color profile (aRGB) in the image when you save it.
finally, i think that doing the "the color space transfer funtion & further down, RGB primaries to sRGB & sRGB primaries" set like this assumes the maps are in srgb to begin with. which i think is pretty safe to assume depending on where you get your actual bitmaps. downloading a logo for a company from their website, you assume it was prepared with srgb in mind. srgb is more or less the standard and has been for a long time.
the cosmos trees i have in a scene right now are all set to srgb/srgb so that means they prepared the leaves and the trunk/branch maps in srgb.