Hotlink protection in multisite mapped domains

Hi, not a WMPUDEV support request, but just an appeal to advanced multi-siters.

It is fairly easy to stop image hot linking on a single site using .htacess, there are plenty of examples out there, but they all need the based domain to be 'excepted'.

So if you have a multi site, with domain mapping, you have in effect one .htaccess file, what are you to do, edit the .htaccess file manually with every new domain?

Any other ideas? Are there perhaps cunning plugins that can deal with this?