How to change system time or force a sync with hardware clock

My laptop is probably running out of CMOS battery, I know I have to fix it soon, but until then, this very annoying issue keeps me from using it.

Scenario: My system clock is reset to 15/12/08 11:00 AM every time I turn on my computer. This has all sorts of side-effects, one of the more annoying being that I can't log into my gmail.

At first I just waited for a time sync to happen, as I have that activated and all. It never happened. I googled and didn't find any way of enforcing a time sync, which I found very strange. Is there really none?

Setting the time and date by hand is also a problem. For my 12.10 installation, the time & date settings are bugged. I remember it being for my last, older installation as well, though. Of course the easiest way should be to just manually edit the date and time fields by entering a new date. This is possible in theory, but the changes are reverted as soon as the text boxes loose focus. The other way to do it is to click the +-buttons for a long, long time. The first time I did that, the changes weren't stored either. I found out that afterwards I have to switch from manual to internet-sync mode and wait ~5 seconds until the in the top left corner of my system the new time is shown, or otherwise it won't have effect.

So a nice solution would be one of the following: Setting the time/date by hand, maybe via terminal, so I can just enter the right values. Or, a command that would enforce an immediate time sync, that I can run after booting. I know I have to change the batteries soon, but this is seriously keeping me from working...

You can set the hardware clock with the command (for example)

sudo hwclock --set --date="2012-12-15 20:49:00"

You then need to syncronise the system clock to the hardware clock:

sudo hwclock -s

Reference: $ man hwclock