We've got a shopping site which we're hosting on a shared host (Mediatemple Gridserver). Some parts of the site need to use HTTPS (checkout etc) but the rest should be using HTTP.

Does anyone know how we can always force the correct use of HTTP/HTTPS for particular URLs? We've had it working in various states but we can't get a request for a page that should be on HTTP but is requested with HTTPS to switch back correctly.

I've had a look around SO but couldn't find a suitable answer to this.