A Teepee is just a role-playing journal, so yes, you need a Soq to actually get one ^.^
That doesn't stop you from getting a custom familiar though, you just have to write that you don't have a teepee yet! The teepee section of the form is only for the custom colorist to look at the stats of the horse, which are an indication of how much he/she has been RPed. The more the horse is RPed, the cheaper getting a familiar for it is.
But if you want just a familiar and not to bind it to any Soq, you don't need a teepee link at all! It is an optional part of the form 3nodding