how to make taxonomywebtaggingcontrol required

Hi,

I have created custom aspx and I have added taxonomywebtaggingcontrols.I want to make those controls required.

Can any body let me know how to make taxonomywebtaggingcontrols required?

I tried the following link but no luck.

http://sharepoint.stackexchange.com/questions/28602/is-it-possible-to-have-a-required-field-validator-for-taxonomy-webtagging-contro

Any help would be appreciated.

Thank you,

AA.