I was running this ROM until a few days ago. I have a stock hboot like you but I had plenty of space using the stock a2sd that comes with the ROM, no need to install run an extra script (even if it did work with stock hboot). From memory, I had 500 or 600MB remaining for apps on my 1GB ext4 partition.
Looking at your TB screen, your ext4/a2sd partition is quite small, showing a 154MB partition (not 1.2GB) with just 978kb free - this would explain the low memory errors that you are getting. It would be worth taking another look at your partition in GParted.
Asus TF101 (B40)
AOKP Milestone 6
Samsung Galaxy S3
Completely stock (for now)
HTC Desire, recently retired, will live its final days/months/years with the LeeDrOiD HD port and a new (non-rooting) owner.
Total noob but loving my new "hobby" (ie. slight obsession) So much to learn around here!