As you can use your browser, you can download the rootsh deb-file
from here http://maemo.org/packages/package_in...86/rootsh/1.5/
Please read the wiki about root access
Download the package to some folder.
Open the filemanager and select this deb-file, it should now
open the appmanager and you can install this package.
After than you should be able to enter
sudo gainroot in a xterminal. At this point you have the
right permissions to change systemfiles like
/etc/resolv.conf. (and all other things, so be careful).

Hope this helps
nicolai