The following steps will allow you to import a Windows based certificate and private key (PFX format) to your LTM:
1) Export the SSL and Key in PFX format from the Certificates MMC on the Windows server
2) SCP the PFX file to the /var/tmp/ directory on your LTM
3) SSH into your LTM and issue the following command:
openssl pkcs12 -in /var/tmp/.pfx -nodes -out /var/tmp/.pem
4) After executing the command OpenSSL will ask you for the password for the private key. If you exported the PFX from Windows with a password, enter it here, otherwise simply press enter to specify a blank password.
5) Once complete, SCP the .pem off of the LTM and use the Web GUI to
import the SSL certificate and key to the LTM