Works fine via bluetooth. Don't know of a way to do it via USB. Use the modem script in the Mac forum for the Pearl. Do a normal pairing and set that script as the modem script along with the correct logins (I know the one for Cingular) and should work fine. EDGE speeds only of course.
Phone: Treo 270/600/650/700w/700p/750v/BB 8800 & Motorola Q >> Future: iPhone