You can't resize the Click Bar ingame, but you can move it by grabbing the blue "handle" above it (where the name of the Click Bar is).
But as far as the size goes you have to type that in, in ISBoxer using the "cell values" (1 cell = 1 pixel). For me, using 60% width and 100% height of the Party Frame ingame, I have mine set to about 164x326 I believe. I did this by eye, but one method could also be to take a screenshot of your Party Frames ingame and open it in Photoshop or similar software, where you can simply draw a box to cover it perfectly and then see the size in pixel values.