I cannot install alpha / beta packages

Hi List, It seems that I can not install packages that are not "stable", like HTTP_WebDAV_Server or Calendar! I only get a useless error message like "Unable to open in read mode '//Calendar'". The are also not listed by the remote-list command. (I think the command should be called "list-remote", but only my opinion...) I guess this is a feature, but is there a simple command/option to install beta/alpha/devel anyway. If not, could you consider this as a feature request? Thank you! Ohh, I just noticed that is is possible to install a certain package version of a "unstable" package. I think an option would be great to turn the package manager to handle with all kinds of packages, also "unstable". Regards, Matthias