How to use nRF24LE1 with Arduino and nRF24L01+
All the nRF24* IC's can communicate with all other nRF24* devices. From the nRF24LE1 web-page:
Fully on-air compatible with all Nordic nRF24L-series, nRF24E-series and nRF240-series solutions

I think you need to stop thinking in terms of "libraries" and start thinking in terms of "how does the device actually communicate".

I recently spent some time working on a nRF library for the atmel xmega (I stole most of the code from a similar project for the MSP430), and there isn't too much going on with the nRF device series. The datasheet is a bit terse, and there is some odd behaviour that can only make sense after you've read the datasheet a few times, but if you're hoping to use a device seriously, you should have a pretty thorough knowledge of the datasheet anyways.

What I would suggest you do is start looking at how you actually communicate with the nRF device. Interestingly enough, the interface to the RF comm tranciever in the nRF24LE1 seems to actually be nearly identical to the discrete nRF24L01+, even to the point of using an on-chip SPI interface for communications between the 8051 core and the RF interface (I wonder if it's two separate dies in one package?). The main differences seem to be the  nRF24LE1+ has discrete interrupt vectors for the RF interface's various interrupt options, while the  nRF24L01+ has a single IRQ pin.

Basically, assuming you write decently modular code, you can probably share significant portions of code between the two devices.