Das,
It may be possible, but it might not be the best approach. The 1-999 can be represented as ([1-9]|[1-9][0-9]{1,2}) and the range 80-65535 can be represented as ([89][0-9]|[1-9][0-9]{2,3}|[1-5][0-9]{4}|6[0-4][0-9]{3}|65[0-4][0-9]{2}|655[0-2][0-9]|6553[0-5])
You should be able to put these together to make a regex. Whether that is a good idea is another question though.
HTH
Cathy