Full range damping?

[Kriist@AOL.COM]

is this a difficult job?(on an upright)
adding dampers up into the highest octaves(so you have full control of 
resonance)
and perhaps have a lever where its switchable to 'regular' piano mode

id like to modify my piano to do this, and i want to know if this is 
something thats commonly done, if its inexpensive etc....

any info appreciated

thanks

rodrigo