Is there an easy way to fit this IC to the b/b??
You are best to skip the breadboard and go straight to a hard-wired version, since there is a lot of power and noise floating around, and the chip has to be heatsinked in any case.
On a perf-board, put pins 1,3,5,7... in one row, and then put pins 2,4,6,8... in the row behind it. A little tricky, but it works. Some pin-bending required.
Once things slow down on my end I will design a stepper driver PCB for it that fits on the Arduino... unless someone else wants to in the meantime? I have the working design with schematics.
Daniel