Transmit is probably your best bet: http://main.system7today.com/software/transmit/transmit.html

On the macbook pro, go into the sharing control panel and enable file sharing. click on the options and make sure FTP is enabled.

Hook the two machines together, and on the LC III, run transmit and type the macbookpro's IP address (which you can get in terminal by typing ifconfig) as well as the short username to your account, and your password.

Then you can transfer files! The LC III will probably appear on the left, and the macbookpro will appear on the right.