Hi camelrex,
If you just want to test the TWAIN scanning on Mac, you can try our TWAIN scanning online demo page:
http://www.dynamsoft.com/demo/DWT/online_demo_scan.aspx
On this demo, you can set scan settings, perform scan, edit image and save/upload image with all browsers on Mac. Furthermore, the demo is developed with Dynamic Web TWAIN, which is compatible with TWAIN specification 2.1 and supports all browsers on Windows and Mac OS.
Note: a small browser plugin will be installed.
You can try the online demo and let me know if you have any question.
Robby