Thanks, that did it. Sorry, I'm a linux noob, so had no idea what that meant, even had to google "how do I install curl on linux"

So...the next bit, I select terminal on the iPod, press home, wait 2 seconds and enter sudo ./oibc
Tried 1, 2 and 3 second delay. Is it just trial and error, it eventually works?
Each time I get the OpeniBoot ASCII art on the ipod (instructions suggest I should see it in the linux terminal?)
and in the linux terminal I get:
OiB client connected:
!<filename>[@<address>] to send a file, ~<filename>[@<address>]:<len> to receive a file
---------------------------------------------------------------------------------------------------------
miu: epoch mismatch
PLL 1: off.
PLL 0: off.
PLL 1: 412000000
Thanks for any further help.