I use one of those Lido floor mounts listed on that page. The arm is mounted to the front seat bolt and it holds the scanner quite well. I just slip the belt clip over the bit of plastic at the top and it holds it well even while off road. I use another floor mount to hold the control head of a Kenwood D710. They have worked well for me going on four years now. I recently added the cup holder mount for a Kenwood 480 control head and it works well too.
I have tried and do not recommend the window suction mount. The vent clip mount is also something to avoid as I never found it to hold my gear well. Others may find it useful.