IIS6 32-bit mode ASP.Net configuration

This shouldn't be something that is needed given how insanely out-of-date IIS6 is, but some firms are still stuck on old platforms.

IIS6 on 64-bit windows can be set to either run natively or forced to 32-bit mode. This is done at the server level, and not the application pool as with more recent versions of IIS. This is a pain.

The ASP.Net tab, used for configuring the version of the .Net framework you wish to use with an application, will only work in 64-bit mode. So if you're running in 32-bit mode, you cannot select the version. This is a pain.

You can though, work around this with the command line. This scenario covers setting a single web-app to use .NET 4.0, and we assume that .NET 2.0 is already installed and working on IIS (in 32-bit mode).

1. Put your app in its own app pool (they cannot run different versions of .NET simultaneously)
2. Open a command prompt in C:\WINDOWS\Frameworkv\4.0.30319 (or relevant version)
3. Register IIS: aspnet_regiis -i
4. Script map your specific web-app: aspnet_regiis -s W3SVC/1/ROOT/[pathtomyapp]/ (replacing [pathtomyapp] with the path to your app - if you don't run on the default site, you'll also have to change the "1" to match your Site ID).
5. Load IIS manager and navigate to 'Web Service Extensions'
6. Ensure "ASP.NET v4.0.30319 (32-bit)" is allowed (or the version you're interested in)
7. iisreset for good measure