add the following to your kernel
Device Drivers ---> USB support ---> USB Serial Converter support --->
USB Serial Converter support [*] USB Generic Serial Driver USB Handspring Visor / Palm m50x / Sony Clie Driver
now hope that your hotplugging is properly installed. maybe you must make /dev/usb/tty/* readable with chmod 666 /dev/usb/tty/*. now if you connct the palm or what ever to your usb port and pressed the hotsync button, the visor and the usbserial modules shuold be loaded and the sync should start.