2nd tonearm on HRX

Hi all, I would like to add a second tonearm to my VPI HRX, can anybody give me some advice on how to do it?
Would a stand alone armpod be a good idea?
The table is on a Symposium Ultra platform, and the stand alone armpod would also sit on the same platform, somebody say the armboard should be connected to the plynth, but how can I do that?
Thank you all, and forgive my english.
Marco