To further expand upon use of CURLOPT_CAPATH and CURLOPT_CAINFO...
In my case I wanted to prevent curl from talking to any HTTPS server except my own using a self signed certificate. To do this, you'll need openssl installed and access to the HTTPS Server Certificate (server.crt by default on apache)
You can then use a command simiar to this to translate your apache certificate into one that curl likes.
$ openssl x509 -in server.crt -out outcert.pem -text
Then set CURLOPT_CAINFO equal to the the full path to outcert.pem and turn on CURLOPT_SSL_VERIFYPEER.
If you want to use the CURLOPT_CAPATH option, you should create a directory for all the valid certificates you have created, then use the c_rehash script that is included with openssl to "prepare" the directory.
If you dont use the c_rehash utility, curl will ignore any file in the directory you set.
