as I found:
Go to
http://www.rfactor.net/index.php?page=devcorner
& download the "rFactor mod development tool pack (Mas utility, scene viewer and more)" - version 2.
Unzip these files.
Copy these 3 files (converter.dlu, material.dlt, texture.dlt) from the "max6" folder into the 3dsMax/plugins folder.
Run the Mas.exe program that comes with the ISI tools & use it to extract all files from the Coreshaders.mas file into the 3dsmax/HardwareShaders folder.
Download the "GMT2 Importer v0.94 by Zoli"
Place importGMT2.ms into 3dsmax\scripts\startup folder.
Go to BTB & export your track to rFactor if you haven't already.
Copy your track folder from rFactor into a place were you want to keep your work files.
(If you exported from btb to "BobsTrackBuilder/xxx_track", only copy the xxx_track folder, not the BobsTrackBuilder folder)
Open 3ds max.
Go to Utilities (the one with the hammer on the far right)
& go to Max Script & in the Utilities drop down menu select "GMT2 Importer"
Change the "Additional texture path" to your tracks directory.
Go to "Import a directory" & navigate to your tracks directory.
Click OK & give it some time to think depending on the complexity of your track.
All going well you should have your track in Max.
Now the fun really starts.