I put half the borax in by dissoving some in a bucket of water and broadcasting it over the pool surface and repeating this until it was all in and then adding half the acid in the same way and then repeating with the other half. The borax dissolved fast as long as I didn't put too much into the bucket of water at a time. I rechecked my pH the next day and found that I needed to add a bit more acid to bring my pH back down to 7.6. Not a big deal.

EDIT: I use the AquaChek borate test strips and I have not had to add any more borax since the initial time. My borate levels are still about 50 ppm!