You will need to use the UPG and a Fanuc Generic Post to start start from. This video is in Spanish, but it is pretty easy to follow along with the changes he is making for it to work. Also, I believe Camworks outputs posts in txt format which is fine for mach 3, bit if you want to change it to tap file extension you will need to copy the .pinf file set from another post in the millsrc folder and change the name inside it and the file extension output from txt to tap. There is a great video on YouTube that goes over doing this.
Here is to adjust the lost:
https://youtu.be/0ohD1SU9a00
Here is some good information about the UPG
https://youtu.be/vXe0s5IbpC4
https://youtu.be/oH0LGqd3se8
You need to learn these so you will be able to tweak it for your machine. If you don't have home and limit switches you will need to do some creative thinking on how to write the tool change operations as most use the home limits to reference the machine before setting the work offsets and then use the machine coordinates for the tool change position. That could be potentially dangerous or cause crashes if the machine coordinates aren't the same every time.
Good luck, it isn't that bad and at the end of it you will have a much better understanding of how posts work and how to adjust them to suit your specific requirements!