As CSP said, you should make 1st ext bigger than the 2nd one. I even don't recommend you to make 2nd ext partition, very rarely rom that require it. Choose 1GB for 1st ext, skip 2nd ext, and skip swap. But if you want to make 2nd ext, try 1GB for 1st ext, 512/256 for 2nd. Remember to back up your sdcard first.
Before flashing the rom, try to wipe all partition except sd card, find it on recovery menu. You should flash the rom first, then flash the a2sd script. From your post, I see you screwed up the order.
To run the script, after rebooting and setting up, if you use the latest DT, type "a2sd reinstall" in terminal. I also usually run "a2sd cachesd" to move dalvik-cache, "a2sd zipalign" for alignment purpose on boot-up.
Add: Arrgg, rugmankc beat me