Diamond allows you to create processors that are FPGAs and place tasks on them in exactly the same way as with CPUs.
Diamond cannot automatically convert from a C task to one suitable for an FPGA; you must supply appropriate VHDL files, or equivalents, for input to the Xilinx ISE tools.
From a configuration point of view, there are no significant differences between a CPU task and an FPGA task; they both have ports that are connected by channels.