Bosses Jag was like that. No user servicable parts...but, after much Google searches, and phone calls, we discovered that there is a fill plug nearly impossible to see. Hidden by a cast metal formation right under the plug. I suspect this trans is the same. All you can do is add fluid. I finally found service data, and to put fluid in this thing required a service computer to show trans temp, and fluid is "supposed" to be added based on temp. THe dealer (closest in D.C.) estimated $300-500 to change the filter and replace fluid. We ordered a filter and pan gasket from an import shop in California, AND th $10 a bottle Z trans "special" synthetic trans fluid...filled it to the plug level cold and caled it good.
I wrote all this cause I suspect this is the same type of trans, if not the exact same one, and you may run into the same crazy hassle dealing with it.