The instructions in Michael's link to extract and patch the MSI are the same for Silverlight v5.0, except the author of that article forgets to disable the updater (among other things) and makes the mistake of editing the MSI directly (step 6) instead of creating a transform. I have attached the MSTs we use to save you a bit of time.
To find out what the various settings do, download the enterprise deployment guide for Silverlight v4.0 (SYNACK's link above is to the v1.0 guide).
Starting with v5.0, there is also a 64-bit version of Silverlight. As with Flash Player, the 64-bit installer for Silverlight contains both the 32-bit and 64-bit browser plugins so you don't need to install both MSIs.
Code:
Direct Download Links
x86: http://silverlight.dlservice.microsoft.com/download/5/5/7/55748E53-D673-4225-8072-4C7A377BB513/runtime/Silverlight.exe
x64: http://silverlight.dlservice.microsoft.com/download/5/5/7/55748E53-D673-4225-8072-4C7A377BB513/runtime/Silverlight_x64.exe