in my experience, if you think you're using too much flux to solder to a trace, you're not using enough. high heat on the iron, smallest tip you got, pre-tin the wire and the trace. prep the trace with a scalpel or hobby knife(i find an xacto blade #2 to work pretty good), then a fiberglass scratch pen(always crash and burn if i forget this step), big ol glob of flux. and JUST long enough to heat the solder, but not long enough to lift the trace. hard to describe, harder to learn, but oh so satisfying once you get it. in my now ancient ps2 portable worklog(really should get back on that thing), i believe i have pictures of the usb soldering, pretty similar to the bluetooth relocation.