@Fred
Got my hmc6352 sensor last week, wrote a library for it which is still in Beta. Also made a simple config sketch to set modes and do a EEPROM dump etc. However when put the hmc in continuous mode it "got mad" values in EEPROM and RAM completely made no sense anymore and I could not reset it for two days. It was working in continuous mode as I could get (uncallibrated) readings at 20 times per second.
I finally got it back to standby mode by a separate sketch that kept on writing to EEPROM the right value and then I pulled the 5V plug.
If you are interested in a "continuous" experiment please send me a PM than I will mail the BETA version. I have to do more tests before publishing the library (but some other projects scream for attention 
Let me know.