It is already possible to obtain more than 10 pet slots. You can obtain one for free with a loyalty box, or by participating in quest a thons when they occur. Then you have the option of paying SP for them from the millionaire center it starts at 20 mill and goes up by 20 mill until 200 mill and then resets again to 20 mill. You can also purchase it with CSC. I will be locking this board up as there is already ways to do this.