I've got one - It sounds more complicated than it is but before you start running switch it to altitude mode then press the start log book button (bottom right) - it should beep and an icon will flash to show its recording. At the end of your run do the same again and this will stop it recording. Then from the altitude mode scroll back (top left button) until you get log book and a log number will appear - leave it for a few seconds and it will give you total ascent (with average ascent per minute then total descent with average descent per minute). If you want to see different logs use the plus/minus buttons to scroll backwards and forwards through them.
If you scroll back one push further than logbook you get history mode which gives you your total accumulated ascent since you last reset it with your highest altitude and date/time you achieved it.
In practice I like knowing the ascent involved in training runs but the really interesting bit is your average ascent/descent rates and they make good targets to try and beat but you cant access them until after the run, nor can you access total ascent during a logbook session, just current altitude (and all the other functions as usual as well such as the watch, barometer and compass). For what its worth it told me that I went up Craghill in one of our local races at 16 metres a minute and came down at 41! - but a more usual average for me is about 11m up and 20 or so down. Its worth bearing in mind as well that if you reset your altimeter at known points during a route this will affect the overall recorded ascent/descent readings.