Help with Pear web installer

Help! I haven't got much hair left!

I'm installing a private copy of pear on a shared host - the web installer has worked beautifully, but I'm struggling to update the config.

I want to be able to change the preferred state to alpha, and to change the channel. When I try to change anything via the config page I get the following message:

config-set (auto_discover, 0, user) failed, channel pear.horde.org

Also, it seems odd that the only way to change channel is by setting the default channel in the config - am I missing another more convenient way to change channel?

Thanks for any help ... Nick.