Please remember: For any issues with the Kies Mini download or installation process or any issues experienced when connecting the Galaxy S 4G to Kies Mini, refer to Samsung (1-888-987-4357 or http://www.samsung.com/us/support/) for further assistance.
So to answer your question (not the answer you want to hear), Samsung 'intended' to enable Mac OS X support via Kies Mini for MAC, however numerous problems manifested as a result and the Kies Mini for Mac OS X option for the Samsung Galaxy S 4G is non-existant.
The T-Mobile docs link provided needs to be revised.
Samsung has provided a revised procedure here for your phone:
Sorry it's not the answer you wanted to hear, but it's the only answer there is
(Again Mac support was really intended, it just never worked right, so that 'feature; never became available.).