first, understand the instructions that your chip can accept, then check the binary code of a JVM. At the doso prompt, type DEBUG followed by the JVM compiler. Then type U and press enter. You will see the first few bytes of code. These are instructions that the 8086 compatible CPU will process when JVM starts.
Now you need to convert these instructions, one-by-one to the VHDL chip you are working with, then create a hardware interface that can program the ROM, and hook the interface to your computer.
Programming experience is required in every case.
If the chip you are dealing with is an 8086, then life is 100% easier, because all you have to do is copy the code to the ROM without any conversion.
This is all I can say, since I don't use VHDL.
good luck