now 10.4.3

Is "Remote Apple Events" enabled in the Sharing Prefpanel?

yes of course.

try this:
move an application to a different location on a remote mac than the same application is on on your local mac.

set remotemachine to "eppc://your.remote.mac.local"

using terms from application "finder"
tell application "finder" of machine remotemachine
set tp to path to (application "YOUR_MOVED_APPLICATION")
end tell
end using terms from

my guess is you'll also get the path to the local rather than the remote copy of the application.

I found the syntax that works:

open (application file id "XXXX" as alias)
-- xxxx is the creator code