FreeBSD supports the bus mouse and the InPort bus mouse from such manufactures as Microsoft, Logitech and ATI. The bus device driver is compiled in the GENERIC kernel by default. If you are building a custom kernel with the bus mouse driver, make sure to add the following line to the kernel config file:
device mse0 at isa? port 0x23c tty irq5 vector mseintr
The bus mouse usually comes with an dedicatd interface card. It may allow you to set the port address and the IRQ number other than shown above. Refer to the manual of your mouse and the mse man page for more information.