Have you try Sommerfeldt Cat.no 162 Overhead spider over the turntable? See view online catalogue from lokshop.

http://catalog.lokshop.de/SOM/2006/page_2.html

But price quite about 130 Euros.

Don't know how can fit with other marklin overhead.

go to the main site of the link steven showed earlier
http://he-lan.com/he-lan/hauptseite/index2.php
click on the E103 movie, and you can see the turntable catenary in action.

If you do not have digitally controlled pantographs on your E-Loks you would have to move them up and down manually in order to effectively use this "spider" catenary arrangement.

I am not sure why you would want to do this if you can use a transfer table (schiebebuhne)!!

I would leave turntable for steam locomotives, maybe even diesels and use a transfer table for your electrics. If you have to spend 130 Euros ($191.00) for this set-up, if you save a little longer you can just as easily purchase a transfer table for around $289.00. Brawa used to make one, Model No. 1180 that was compatible with Maerklin and you can find them occassionally on E-bay. In fact there is one seller right now offering one for $124.00!! You can easily configure catenary for use with these tables.

Regards (a Scot in Wisconsin)