Tool needed to remove bottom of A1048 keyboard?

Well, for me, the model number you mentioned is actually an Airport express model, however, there is a keyboard with the model number A1048, which I think is what you are talking about. In order to remove the bottom, there aren't really any special tools, you just need a really small torx screwdriver. I clean these models by popping all the keys off, which is pretty easy if you pull them up from the corners, letting them all sit in warm water for a few minutes, then lightly scrubbing each one. When all they keys are off, you can take a q-tip and clean around the key mounts that are under the keys. Doing this for me usually takes a keyboard from being dirty and sticky (and sometimes hard to use since keys stick and get stuck) to looking like it was just made. The bottom cover is normally the last part, and I just have to use really small torx screwdrivers (really really small) to remove the screws (there are also screws under the rubber pads on these models).

I got an older keyboard than yours to go from this:

To this:

Hope this Helps