I have some strings that have been encrypted using the PHP function crypt().
The outputs look something like this:
$1$Vf/.4.1.$CgCo33ebiHVuFhpwS.kMI0
I believe the answer to my original question is no, you can't convert from one format to the other.
The hashes generated by php crypt() appear to be generate by a version of the FreeBSD MD5 hash implementation created by Poul-Henning Kamp.
http://people.freebsd.org/~phk/