CSR generation for PositiveSSL and PositiveSSL WildCard with Apache2/OpenSSL see: CSR Generation: Using OpenSSL (Apache w/mod_ssl, NGINX, OS X):

 openssl req -nodes -newkey rsa:2048 -keyout myserver.key -out server.csr

To generate the CA bundle see this article:

 cat COMODORSADomainValidationSecureServerCA.crt COMODORSAAddTrustCA.crt AddTrustExternalCARoot.crt > your_domain.ca-bundle