I did not understand , do you want to powerup from internet or from lan ?
btw as far I know as soon it's OFF there is no way to power it up again .
If you want to wake from intenet you could try to use HamachiX.
Hamachi it's a kind of VPN ( Virtual Private Network ) that will allow you to see the museum mac's in your home network over the internet . I think then you should be able to wake up the museum's mac's from home .
If you need a good remote controller , you should think to use ARD http://www.apple.com/remotedesktop/
anyway , why do you want to powerup powerdown your mac's ?
Can't you just restart it ?
did you set RESTART AFTER POWER FAILURE ? ( systemsetup -setrestartpowerfailure on )
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