'03 QX4 spark plug seals

[mokume]

I intend to replace both valve cover gaskets on this vehicle, it's my understanding that the spark plug tube seals are molded into the underside of these plastic covers.
Consequently, the entire cover must be replaced, Nissan does not market replacement seals.
Fel-Pro makes a 'spark plug tube seal set', part number ES 72481 which are designed to replace the original seals, has anyone used these with success?