I wanted the same thing, and found out that the whole search block is formatted as <div style="cbUserListSearchFields">
So in my normal website template.css with the main column 70% and a side column on the right, I added:
.cbUserListSearchFields {display: block; position: absolute; top: 390px; padding: 0px 0px 0px 695px; width: 200px;}
This worked fine, the search block is on the left and the list remains in the main column. Only related problem is that the search block is initially hidden. See
www.joomlapolis.com/forum/153-professional-member-support/222803-always-show-search-fields#234272