Creating a PFX file from a CRT and KEY using OpenSSL
You can easily create a PFX file to install your SSL certificate in IIS from KEY and CRT files using OpenSSL:
openssl pkcs12 -export -out your.domain.name.pfx -inkey your.domain.name.key -in your.domain.name.crt
or if you have the root CA and intermediate certificates the command is:
openssl pkcs12 -export -out your.domain.name.pfx -inkey your.domain.name.key -in your.domain.name.crt -in intermediate.crt -in rootca.crt