Sorry if I'm still confused, but you want to focus your training, for a while, on increasing your deadlift, correct? So instead of squatting, for a while, you want to use a leg press thingy while you focus on your deadlift numbers?
Did I get that right?
If I did, then my question would be: Do you expect to help increase your deadlift by using the leg press thingy? Or is it just to do some quad work while you work on your DL? The reason I ask, is that I don't think working your quads directly will help your DL much.
There are many other ways of increasing your DL rather than a leg press. I would suggest investigating some of those other methods to see if they will do what you want. You can still back off the squats for a while, like you are already planning to do, just don't need to buy the leg press thingy.
.02,
Joker