Hmm... quite an interesting request. I'm sure there'll be better solutions and this one might be quite dumb, but start this Autohotkey script on the computer and remotely create a blank file called "CapsLockOn" or "CapsLockOff" to enable/disable Caps Lock. (Use "SetCapsLockState,AlwaysOn" or "SetCapsLockState,AlwaysOff" if you don't want to force the CapsLock state.)
;#NoTrayIcon
#persistent
SetTimer, CapsLock, 1000
return
CapsLock:
IfExist,C:\CapsLockOn
{
FileDelete,C:\CapslockOn
SetCapsLockState,On
}
IfExist,C:\CapsLockOff
{
FileDelete,C:\CapslockOff
SetCapsLockState,Off
}