Activating swap at boot with an init.d script? I have a rom that supports swap, but the swap script is missing.

How would i make that swap script manually?

I.E: What code would be in the file /etc/init.d/07swapon?
How about this? 

Open a console, navigate to the android SDK tools folder.
Type "adb mount /system", without the quotes doh!
Type "adb shell".
At the shell copy paste the following commands one by one and press enter after pasting them.
echo "#!/system/bin/sh" &gt; /system/etc/init.d/05userinit
echo "swapon -a" &gt;&gt; /system/etc/init.d/05userinit
echo "/dev/block/mmcblk0p3 swap swap" &gt;&gt; /system/etc/fstab
chmod +x /system/etc/init.d/05userinit
chmod g-w /system/etc/init.d/05userinit
chmod o-w /system/etc/init.d/05userinit
chmod g-w /system/etc/fstab
chmod o-w /system/etc/fstab
exit

Now you are back at the normal command prompt, type "adb reboot".
Device will reboot, when its done open a terminal and type "free".
It should show swap space allocated.

And with some programs in memory you can see swap being used:

adb shell
free
total used free shared buffers
Mem: 407860 399940 7920 0 872
Swap: 249596 16596 233000
Total: 657456 416536 240920


Information from here