first do a search for bluetooth dun
there is a secret way that you have to turn it on on teh phone. there is a post in this forum that tells you how.
then just add the device on your mac and dialup networking should be an option for you to choose on your mac of the available services.
You cannot use USB tethering, i assume for the same reason that markspace cannot get usb sync working. you can only use bluetooth.

as for me, when i did it i found the results unnacceptable. slow connection that dropped all the time and froze my phone.
instead i purchased the kyocera kr1 which is a wireless router that you plug an evdo pcmcia card into (which i already had) that solution works a lot better. if you need more info on that pm me and i will send you to the right place.

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Tanguy de Courson