Thanks Spamly,
Tried that but when I check the file system I can't see any difference to /tmp ?
Here's the commands that I used...
#mkdir /space/swap-dir
#mkfile 100m /space/swap-dir/swap
#swap -a /space/swap-dir/swapfile
#df -h
/dev/dsk/c0t0d0s0 5.8G 2.2G 3.5G 40% /
/proc...