The process is similar to any digital design using VHDL. However, you may have to carry out algorithm modifications to simplify the hardware. Some issues that are relevant to ANN implementation in hardware:
(a) algorithm to architecture mapping
(b) algorithm simplification for harware mapping
(c) target tech...FPGA or custom ASIC
a good source would be IEEE journals on previous projects. It would come under the IEEE proceeding for neural networks. Search under the "N" category.