Bottom line is, you need two or more cables to your DVR location.
If you use a multiswitch, you need all 4 lines connected between the dish and the multiswitch. This means that you cannot put the multiswitch at the end of a single (or even dual) coax run - it will only work properly with all 4 input lines connected.
So you either need to (a) run two lines from each dvr location to the dish, or (b) select a location that is convenient for the multiswitch, then run four lines from the dish to the multiswitch, and then run two lines from the multiswitch to each DVR. If you think you will ever want more than two TV locations, or more accurately if you think you will ever want more than four coax lines hooked up at one time, then you should put the multiswitch in now and run all of your wiring to the multiswitch location.
If you search through these forums, you will find several threads that discuss why you need to wire this way. It has to do with the fact that the coax is a 2-way street. The receiver sends signals to the dish, and the dish sends the applicable channels back to the receiver. Not all channels from all satellites, are on the coax at any given time.
Carl