In 3ds Max > Select mesh > Add UVW unwrap modifier > Open UV Editor > Options > Preferences > Unwrap Options Window will open
Here are the options you’ll need to change in this window:
When you hit OK make sure in the Edit UVs window that you select the Snap to Grid option in the far bottom right (grid icon with a magnet) to get the vertices to snap to the grid when you move them. You will need to make sure that each vertice (only if it’s a straight edge, no need to worry about make suring curved surfaces are falling on on a grid point)
This is important because any hard edge that falls between a grid line will be rendered as shadowed. This can cause softer shadows that can cause bleed and such.
If you’re still having trouble feel free to post the asset here or send me a link via the forums in a PM and I’ll take a look to help further. 
Tim