Starting with the HEW project for the RDX, which has a 100-pin RX-62N on it, I ported the RDK demo to my own RX-62N board, which has a 144-pin RX on it and works with a Linux development engironment. I've attached the Makefile for anyone who wants to get started down that route... The "gsi" file is the generated linker script from HEW.
My board: http://www.delorie.com/electronics/rx/os-board.html
Makefile
RTOSDemo_Blinky_auto.gsi