I think the Spektrum R/C equipment uses Cypress wireless modules which are similar to but not compatible with the Nordic nFR24s.
The Deltang wireless modules for model trains etc use Cypress modules and a while back I wrote my own code for the Atmega 328 on my Deltang modules and wrote about it here. Feel free to make use of it but I do not plan to provide any support as I have forgotten all the details. Nobody seems to make a simple breakout board that would allow the Cypress wireless to be used with an Arduino as easily as an nRF24.
...R