SSRS and ssl certificates

(This is a cross post from the MSDN forums, as no has repsonded after 5 days.)

I have a problem with creating and using a self-signed ssl certificate for SSRS 2008 and there doesn't seem to be any clear instructions on the net.

Setup - server1 (windows server 2008 w SP1) hosts a website. server2 (also windows server 2008 w SP1) hosts SQL reporting services. (SQL is standard 2008 x64 w SP1 CU1). Both servers are on the same lan & domain.

Base setup:
Configure the website on server1 and SSRS on server2 to use http. User connects to the website on server1 and can access the reports on server2 with no problem.

Secure setup:
Purchase and install a certificate for server1. The clients now connect to the website on server1 using https no problem. server2 is still configured to use http. SSRS rejects the communication from server1.

My options are :
a) Use a self signed cert on server2.
b) buy another ssl cert for server2.

The current method of creating a self-signed certificate without installing IIS 7 on server2 is:
http://msdn.microsoft.com/en-us/library/ms186362.aspx

When I run the makcert command:
makecert -r -pe -n CN="server1.mycompany.com" -eku 1.3.6.1.5.5.7.3.1 -ss personal -sr localmachine -sky exchange -sp "Microsoft RSA SChannel Cryptographic Provider" -sy 12

I get the error:
Error: Save encoded certificate to store failed => 0x5 (5)
Failed

If anyone has any insight on the following, it will be greatly apreciated.
a) Will a self-signed cert be enough for server to server communication?
b) Is the "-eku" and the "-sp" options correct for SSRS?
c) Any ideas on using makecert command to avoid the error above