pico:
When I move the installation to another directory (\Arduino) the IDE complained it couldn't find avr-g++ (even though the path it showed was in fact correct after moving the directory). I assume there is some registry value that is causing issues?
How are you moving the installation? You need to uninstall it and then install it in another path (or manually change the PATH environment variable)
pico:
I copied the "tiny" subdir into the "\program files\arduino\arduino ERW 1.0.2\hardware" subdir, but no go... they didn't show up in the boards list at the next restart.
You need to edit boards.txt (try to backup the old one because it contains the "ram" size, and that's not a default thing)
BTW, did the jrlp's suggestion worked for the protocol issue?