Unless the Panny Plasma talks 418MHz the only way you will be able to do this is to purchase an RFX6000/6500 if you can find one on Ebay. The remote communicates via RF with the extender and the extender converts RF back into IR.
The RF remote of a product is almost completely unlikely to operate the same way as the RF remote of another product, even if of the same brand.
RF is always designed with a transmitter (the remote) paired to a receiver (in the TV) designed to receive signals only from its own remote. When Lyndel speaks of 418 mHz, he's defining the single frequency range where the Pronto RF system works.
[Full of gluten since 1965!] A good answer requires the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
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