Here is the procedure I used to upgrade mine.
I had problems getting it to boot initially, but it turned out to be a combination of having the SODIMM seated, the BIOS chip seated, and the correct CPU multiplier all at the same time. Once I got those things straightened out it works great.
Boot up to CMOS setup (CNTRL-ALT-ESC) and select CHIPSET FEATURES SETUP
SET bank X/X Dram timing to 8 ns
SET SDRAM cycle length to 2
Save & exit
Move SW3 to SW1 to set the multiplier, and remove R130 (0 ohm) and set the multiplier to 2.0 for the Winchip
Solder jumpers onto R329 & R330 pads for 100Mhz FSB (I used R130 for one of them)
Here I booted with the Winchip and verified that the system works at 100Mhz FSB
Enable split voltages by moving R60/R61 to R184/R185
Clip all the pins on the PT6702 (pins 1-23)
Solder a dip switch to pins 3,4,5,6 and the other side to pin 13(data sheet says use pin 13, not pins 14-18 as voltage programming ground) Set the switches for 2.00V per the spec sheet (pin3 open, pin 4,5,6 closed)
Solder a wire from pin7 to pin13 of PT6702
I did not connect a pull-up to pin2, Power Good, since this is not required if this signal is not used
Connect three 22 AWG wires, one to pins 10,11,12(Vin) one to pins 14,15,16,17,18(GND) and one to pins 19,20,21,22,23(Vout)
I mounted the PT6702 along the edge of the case on the processor side, below the speaker. I placed one of the legs under the speaker clamp, and tied it to the clamp with a tie-wrap. I glued the other end down with some RTV glue.
Connect the wire from Vin (pins 10,11,12) to the Big square pad of Q16
Connect the wire from Gnd (pins 14,15,16,17,18) to Gnd, I used the big square pad with the mounting screw in it,
to the left of C154
Connect the wire Vout (pins 21,22,23) to the next biggest pad of Q16
(I didn't add any additional capacitors, since there is already 1000mfd on the IO.)
Connect a schottky diode from pin8 of PT6702(anode) to the smallest pad of Q16(cathode)
Solder a .010 ohm smt 1 watt resistor in parallel to R302 (to get a higher current limit if necessary, for clocks higher than 3 x 66 (default).)
WITH THE CPU SOCKET EMPTY, test your Vcore by powering up and measuring from GND to the Vcore pads of the now-empty R60/61, and voltage at pin 3 of Q16, and check that it goes off when the power is off (with the power supply connected)
Set the SW1 multiplier to 3.0 (these things don't seem to boot higher than 300Mhz)
Install the K6 processor (make sure you have a heatsink & fan if you are going to leave it running for more than a few seconds)
Let 'er rip!!!
to jump from 300 to 450 Mhz in the autoexec.bat
I have some pictures to post, but haven't downloaded them to my PC yet. I'll try to do that this weekend.
Thanks to badflash, rnunes, Tinman2, and others who I plagarized much of this from.