Yes, you can either use the outbound command for older versions of the pix software 4.x
or access-list with access-gourp out from version 5.x and later (like a router access-list)
see for examples :
http://www.cisco.com/univercd/cc/td/doc/product/iaabu/pix/pix_v44/pix44cfg/pix44exs.htm
http://www.cisco.com/univercd/cc/td/doc/product/iaabu/pix/pix_v50/config/examples.htm
http://www.cisco.com/warp/customer/110/single-net.shtml