There are already various configurations for well known packages available in the MetacelloRepository project.
With a pharo image installed Metacello can be used to load a specific (or the latest) versions of Seaside:
(Smalltalk at: #ConfigurationOfSeaside30) loadLatestVersion
Tudor Girba now created a basic version of a browser called "Metaceller" for managing Metacello configurations that are already loaded in the image. Read more here.
To load in Pharo evaluate:
(Smalltalk at: #ConfigurationOfGlamoroust) perform: #loadDefault.
After loading you can open the tool using: