I have already managed to add Paypal as a payment option, just unable to select it as billing method.These are the steps I have been using:

Browse to "http://billing.microsoft.com"
Log in, get my email with security code.
I am now at "https://commerce.microsoft.com/PaymentHub".
I click on "Subscriptions", and the select "MSN Narrowband Metered Access".
Then I click on manage and a pop-up appears with "change payment option" already selected, so I click "next".
Another pop-up is displayed with the text "Change the payment option of 20: MSN IA Narrowband(4.95/mo)from Visa xxxx7024 to:"
"add payment option" and "back" are the only available choices on the screeen.

I click on "add payment option" and a new window appears that lets me set up a new payment option.
I can set up as many payment options that I want and they will then appear in my list of payment methods, but I can't find a way to select that method as the method I want to use to pay my bill.

Now I have 2 payment options.  One is for my VISA card which has been cancelled because the number was stolen, the other method is Paypal.  If I try to remove the VISA method, a pop-up appears that informs me that I cannot remove the VISA method until I attach another method.

I click "change payment method" and I am back at the same pop-up that I saw earlier, allowing me to set up a new payment method, which appears on my list of payment option on the "payment options" screen, but I don't know how to attach it to the subscription.

Can you help please? Thanks.