Hi Andrew,
I tried the A1111 extension in the Forge Colab notebook but it caused it to crash while loading. I found the official Forge version at: https://github.com/deforum-art/sd-forge-deforum
but there were loads of errors while loading and while the session loaded ok and the extension appeared in the list, there was no deforum tab. Others seem to have got it to work according to the forum linked on the readme.
Not a biggy but I can let you have the error log if you want to have a look