You can always use something like Quicksilver to assign keystrokes to applescripts of the following general pattern:
Code:
on run
tell application "OmniFocus"
tell front window
set lstTrees to selected trees of sidebar
if (count of lstTrees) < 1 then return
end tell
repeat with oTree in lstTrees
set oValue to value of oTree
if class of oValue is project then
set status of oValue to on hold
-- OR
-- set status of oValue to done
-- set status of oValue to dropped
-- set status of oValue to active
end if
end repeat
end tell
end run