From DSL Wiki
This is a tool that uses wget to download a specific myDSL extension from your favorite DSL mirror. It is mainly used by the MyDSL Extension Tool, but it can be used non-interactively by the user.
The snag is that you have to know exactly what file you want, and where it's located.
mydsl-wget appname.dsl directory
"directory" is the directory name within the myDSL mirror. Currently (DSL 3.0) available directories are apps, games, gtk2, multimedia, net, system, themes, uci, unc, wm_apps, and testing. Testing should be used only if you don't mind if something happens to completely ruin your system =o)
"appname.dsl" is the filename of the myDSL extension. If you want to save the file to a specific (existing and writeable) local directory you should specify the directory as part of filename:
mydsl-wget /home/dsl/mydsl/audacity.uci uci
Otherwise the file will be downloaded to the current directory.