I'm looking at protocols like the Aloha protocol at the MAC level. How hard is it to programme such protocols (lets say in C language) for real life working devices.
where can i learn such low level programming? Does C language have special methods/classes/functions that would help programme MAC layer protocols?
It depends on how much experience with such things. If you have none, then yes, it's very difficult to get right all the time.
You can get a feel for that sort of thing by reading the source for network code for which you already have a description (netcat's a good place to start although I think the code is messy).
C doesn't have special functions for such things. But you'll end up doing read/write on some file descriptor (on Unix anyway) for the actual I/O and maintaining state with your own data structures for the protocol.