Humayun, Rather than spend dollars on something for single purpose use, you may want to consider the ADM mini dovetail system reviewed here
http://www.users.bigpond.com/lansma/...and%20delivery. (BTW this site has a lot of detail on LX90 and astrophotography.)
http://www.astro.premcom.com/ADM/ADM...l%20System.htm I think IIS member Mick Pinner is also making some piggyback accessories, it may be worth PMing mick to see what he has to offer.