Hi,
In order to develop an ANT product, you would need an ANT chip based solution with the ANT protocol integrated in it. There are two types of ANT chip based solutions available:
1) Single ANT chips such as nRF24AP2, nRF24AP1 and CC257x
2) ANT chipsets such as AT3 chipsets
For more details on those ANT chip based solutions refer to "Products" section of the ANT website (link below):
http://www.thisisant.com/products
Therefore, you can't use the nRF24L01+ because it doesn't have the ANT protocol embedded in it. Also, you can't program the ANT protocol on your own uC because the ANT protocol is proprietary.
As an ANT developer, you need first to obtain an ANT based solution (either ANT chip/chipsets or modules);with the ANT protocol integrated in it, then write your own user application that utilizes the ANT protocol and its features.
You can get an AT3 module or an AP2 along with a micro-controller for your development. Also, there is sample code available for most device profiles.