Setting sessionState customProvider programmatically

In my web.configfile, I declared 2 sessionState providers:

<sessionState mode="Custom" customProvider="SessionProvider1">
    <providers>
        <add name="SessionProvider1" ... />
        <add name="SessionProvider2" ... />
    </providers>
</sessionState>

Now I would like to switch customProviderto SessionProvider2at runtime ... Is there a way to do this without changing programmatically web.config?

Thank.