I have a directivo with 2 lines coming in. I would like to put an a-b switch in line 2 before my directivo and add another standalone tivo for recording purposes. Will this work?? I don't want to keep switching back the cables back and forth and figured that flipping the switch would be the easiest way.

I'm not sure if it will work at all but I do know that it won't give you an advantage except for more space.

if receiver B is using line 2, then receiver A can't use it to either record or display.

In other words, you could not record 3 programs at once or watch 1 and record 2 at the same time. What you want to get is a multiswitch for your dish, then you can hook both receivers up. I think it would be a 2x4 multiswitch that you want if I understand all this correctly.