well, that really depends on how you set up the material in Max.

If you are talkinag about a material where you have two textures, with an alpha mask to blend them together, this is basically what  you'll want:

you'll connect your two textures to a LinerInterpolate and use a texture coordinate node to tell the material what UV channel it should be using (keep in mind that UV Channels in UDK are 1 less than Max, so in Max, map channel 1 becomes Coordinate index 0 in UDK)

you are doing a composite material with 3-4 materials, each with unique alpha masks, each on their own UV channel?  or are you doing a multi-subobject where different pieces have their own material?  it might be helpful to see what your material looks like in Max, and how it is being applied to your model. compositing 3-4 materials seems excessive and will be pretty rough on processing especially if you have multiple in your sceen.

had to test out a couple things, but you can do multiple lerps like this:

just make sure you play around with the order that you connect the materials and their alphas so that they display properly.  Alternatly, with a large terrain piece like that, you could turn it into a mesh paint material by using Vertex Color nodes like so:

With the set up above, what ever you paint Red will show the light dirt, what ever you paint blue will have the grass.  Also, if you create an alph for the grass that creates a cutout of the blades, and put that as a Texture Sample in front of the Vertext color nodewhen you paint, it will make a really nice blend between the grass and material below, as if the grass is actually on the dirt instead of just fading in and out.

Also, if you properly unwrap your model ignore the TexCoord node (I was being lazy)