firth, this assumes you know how to load modules, how to compile a kernel, that you are using a 2.4.x series kernel, and that marsupials can be amusing.

1. get the latest lm_sensors package from http://www.netroedge.com/~lm78/download.html
1a. get the latest i2c package from http://www.netroedge.com/~lm78/download.html
1b. get the latest kernel 2.4.x seriese kernel source from kernel.org.(this is written for 2.4.6).
2. untar the kernel source, the i2c source, and the lm_sensors source(i will assume you are working in /tmp).
3. go into the i2c source dir.
4. make the patch for the kernel source, './mkpatch/mkpatch.pl . /tmp/linux > /tmp/i2c-patch'.
5. apply the patch. cd ..; patch -p0 < i2c-patch;
6. make the patch for lm_sensors, this uses the same process as the i2c patch. cd lm_sensors; ./mkpatch/mkpatch.pl . /tmp/linux > /tmp/lm_sensors-patch;
7. apply the patch. cd ..; patch -p0 < lm_sensors-patch;
8. now time to compile lm_sensors. cd lm_sensors; ./configure; make; make install;
9. now compile your kernel, make sure to compile the i2c support. under 'I2C mainboard interfaces' compile 'Pseudo ISA adapter' into the kernel. Under 'Hardware sensors support' build 'VIA 686a Integrated Hardware Monitor' as a module. Those are both in the character devices section.
10. compile and reboot with your new kernel.
11. load the via686a module.
12. now run the 'sensors' program, if it has worked right you will see some output, the numbers will be all wrong, but there should be numbers.
13. now you need to edit the config file for sensrs, /etc/sensors.conf. Here is what you need to put in it:

chip "via686a-*"
    label "2.0V" "CPU core"
    label "2.5V" "+2.5V"
    label "3.3V" "I/O"
    label "5.0V" "+5V"
    label "12V" "+12V"
    label fan1  "CPU1 Fan"
    label fan2  "CPU2 Fan"
    label temp1 "CPU1 Temp"
    label temp2 "CPU2 Temp"
    label temp3 "SBr Temp"
    set in0_min 2.0
    set in0_max 2.5
    set temp1_hyst 55
    set temp1_over 65
    set temp2_hyst 55
    set temp2_over 65
    set temp3_hyst 60
    set temp3_over 65

14. now run sensors -s
now when you run sensors it should have the correct data.
you will need to load the via686a module after every reboot, i sugest putting it in an init script.