SSL certificate for Active Directory (to use LDAP over SSL, aka LDAPS)

Hi,
We need to support LDAPS protocol with AD, for one of our products.
Currently we use LDAP, and I understand that for LDAPS the AD server must have a certificate.
I want to do some testing for the new product with LDAPS, and for this I need some temporary certificate.
Will the free Comodo SSL certificate work for this purpose?
What is the standard procedure to obtain a certificate for an AD?
Cheers,
Gilad.