if you want to make it where it's not a swap partition, but just an empty file on your disk, you can use the mkswap, swapon, swapoff, dd, and mount commands (read their man pages) and then write it in fstab. (read the man page on fstab as well)

first create a new swap file wherever you want with dd, whatever size you want (it must be contiguous sectors)
then mkswap it
then swapon it
then swapoff your partition
then change your fstab to point to the swapfile

here's mine:

`/swap.img none swap sw 0 0`