I assume that your printer is using CUPS. The best way to do this would be using the command line.
You can print the odd numbered pages, then turn the paper over and print even numbered pages using the following:
Code:
lp -o page-set=odd filename
then turn the paper over and:
Code:
lp -o page-set=even filename
More information about printer options can be found at
http://localhost:631/sum.html
I hope this helps
--Ian