1. Download eclipse (I downloaded for OSX)
2. Download the RCP delta pack and install it into the eclipse distribution.
3. Run eclipse with a clean workspace. Alternatively you can switch workspace from the File menu of eclipse.
4. Create a plugin project (the name does not matter - I called it eclipse)
a. Uncheck the 'create java project' under project settings
5. Create a new product configuration with the following settings:
a. Name = eclipse
b. Product ID = select new and create eclipse.product
c. select based on features
d. Under configuration tab, select 'Add all' and select all the features displayed.
6. Select plugin.xml and under build tab select plugin.xml to be included into the binary build.
7. From product configuration select export product.
a. Select 'Export for multiple platforms' under Export options
b. click 'Next' and select the platforms that you need.
At the end of these steps you will have eclipse for all the selected platforms. From your installation copy the config.ini (eclipse/configuration folder) and eclipse.ini (eclipse folder or eclipse/Eclipse.app/Contents/MacOS folder on OSX) to each of the target eclipses.
That is all. Now you have eclipse for all the platforms you need and you have saved some bandwidth and made net a better place by reducing the choking of the wires :-).