Hi Peter,
the "russian hack" is unofficial firmware update that unlocks some additional functions in 300D/350D/400D Canon cameras.
As far as I know mirror lockup and ISO3200 are not part of functions available in original Canon menu for 300D/350D/400D models and most likely functions for 20D/30D/40D models. However these functions are there and they are just hidden in 300D/350D/400D models by Canon. The "russian hack" update just makes them available for use. It's called "russian" because it was written by a guy from russia :-)
You can access all unlocked functions as easy as you usually access functions in Canon menu. All new unlocked functions will be in the last tab under "Custom functions" menu. IS03200 is available at the same place where you usually change ISO. It appears as the last option on the ISO list after 1600 with only difference that instead of displaying 3200 you will see "H". If you select it it will mean you just set your camera to ISO 3200.
Below is a link to more details about this firmware
http://www.bobatkins.com/photography...ware_hack.html
There must be even more detailed guides about it available on the Internet.
cheers,
Mike