I'm slightly struggling with the script bit actually. I managed to get a command prompt and can change folders, ls etc but that's about it. I can't change permissions on the file. Running it manually (i.e. "sh file") and most things in your example don't work.

Tasker seems to expect to SL4A to be installed too. SL4A seems to have some issues with my phone.

Sorry don't have a lot of time right now. Thought this would be a bit easier to test.