This paper presents the use of SystemC to model communication channels for asynchronous circuits at various levels of abstraction. Our channel library supports transactions through a CSP-like interface (implementing send() and receive() commands) as well as through one of many specific handshake protocols e.g. 4-phase-bundled-data push etc. Our SystemC implementation enables a seamless design flow which makes possible: (i) modeling and simulation at different and mixed levels of abstraction, and (ii) easy use of different data types and handshake protocols on different channels in the circuit being designed. The paper also illustrates the use of this design flow for several asynchronous Networks-on-Chip all the way from system level to handshake components.