Ah ha! Success!

On the page www.gronmayer.com/n800/repos/

scroll down to the "Minimo" entry (4th one down) in the 770 column (while browsing via your 770) and click on the link. It will add a new repository, and then minimo will show up in the applications manager and install!

What seems strange is that the repository it seems to adds is:

www.maemo.org/minimo
bora
user

Which I thought I had added already. Whatever - it works

Thanks again for the help!