Just import the OBJ sequence, and then adjust the material. It doesn't matter what's in the mtl file, because most of the time you need to rework the materials anyway, when you import objects.
Be sure to type in the correct line when you import the sequence. That means when your sequence goes from xxx.001.obj to xxx.200.obj you need to import it using this line: xxx.%03d.obj , because you have 3 digits (I hope this is the right expression). When your sequence goes from xxx.0001.obj to xxx.1000.obj (4 digits!) you need to change the 3 to 4, that means xxx.%04d.obj.
I hope what I wrote makes sense.