Not the most efficient alternative, but if you send the XML as base64 encoded text you shouldn't have any problems. 

return RPC::XML::base64->new( $buffer );

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In reply to Re: Sending application-specific XML as a string paremeter to an RPC::XML method. by Fletch
in thread Sending application-specific XML as a string paremeter to an RPC::XML method. by nenbrian

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