Set Corporate access level on successful VAT check

Hi,

I have just upgraded to the business edition of hikashop to allow more control over access levels. I have created a Joomla user group Corporate, and have applied a percentage discount across all products for the Corporate users. I now need to automatically assign the Corporate user group to anyone registering with a valid VAT number, when the online check has been successfully performed. Is this possible?

Thanks

PS, One more thing: How can I remove the modules displaying on the checkout pages? I have a joomla login module and a hikashop filter module that will not disappear.