Groovy-Eclipse plugin installation

I have been trying to install Groovy Eclipse plugin using update sites listed in Groovy, but always failed with errors such as "No repository found containing:org.codehaus.groovy/osgi.bundle/1.5.7.20081120_2330" or missing dependency etc.

Finally, I downloaded the snapshot (archived zip) to local and install it successfully.
# Help -> Install new software -> Add...
# Select the location of the zip you just downloaded
# Install as you would from the regular update site