Hi Chasman,
I have an 04, the button as you call it is called the "Tripmaster-Switch with Clamp" part number 583.14.069.200, it is shown in the 04 parts manual as an 03 item. The speedo on my 04 has a different part number shown in the 04 book than the 03 book has. The 03 book does not refer to or show the "Tripmaster-Switch.
As to what other functions are on the speedo, look at the 04 Owners Manual; on line at the Husaberg Factory Site, for a complete 6 page narrative..
It provides for:
2x trip master plots
2x chronometer for the lap time
average speed
maximum speed
clock
display in miles
It has 12 or so display modes for readout and reset, it allows adjustability of everything but tire size, total hours, and total miles.
However, I cannot guarantee that all of these functions are available on your 03 Speedo, some other 03 owner will have to advise you of that.
Regards,
Joe,