Using ASPNET_REGIIS to encrypt system.webserver / rewrite / providers

Question

I'm using ASPNET_REGIIS to encrypt different subsections of my web.config file.

I can encrypt the SMTP password using:

ASPNET_REGIIS -pef "system.net/mailSettings/smtp" "C:\My Project"

However, I can't encrypt the system.WebServer / Rewrite / Providers section using:

ASPNET_REGIIS -pef "system.webServer/rewrite/providers" "C:\My Project"

The root folder "system.webServer' can be encrypted entirely using:

ASPNET_REGIIS -pef "system.webServer/rewrite/providers" "C:\My Project"

None of the sub sections (ie. httpErrors or httpProtocol) work.

The system.webServer/rewrite/providers section has a database connection string in it which needs encrypting.

I don't think there's a way for the rewrite module to access the section (better option), but I also don't want to encrypt the entire rewrite section.

Anyone else figured this one out?