forum.thinkpads.com
specifically: http://forum.thinkpads.com/viewforum.php?f=6&sid=44974ccddb7711b048752ce644d5a9d7

701C Hard Drive Removal and Re-Installation Instructions

1. Close the LCD.
2. Remove the battery pack.
3. Locate the hard drive compartment (next to the battery compartment) on the left side panel.
4. Slide the hard drive out of its compartment.
5. Remove the 4 Torx-6 screws that attach the hard drive to its bracket.
6. Gently remove the old hard drive from the bracket's connector.
7. Carefully attach the new hard drive to the bracket's connector.
8. Replace the 4 Torx-6 screws to secure the new hard drive to the bracket.
9. Slide the hard drive into the hard drive compartment, making sure that it is firmly seated.
10. Replace the battery pack.

Once you remove the hard drive itself from the caddy, it's just a usual 2.5-inch, 44-pin IDE interface. You can use the circuit board of pretty much any 2.5-inch USB-IDE enclosure and access it via USB. (The drive itself probably won't fit in the enclosure since it's 12.5mm thick.)

The PCMCIA slot on a 701C is a 8 or 16bit PC Card slot. It is not compatible with the newer CardBus adapters. 

it has been suggested to de-solder and remove the existing battery on the board, noing the +ve and -ve terminals and sldering on a cmos battery from a THINKPAD 600 or similar, by removing the connector and soldering the wires to the board. I have to say that this did absolutely nothing for me and it was a bit of a pain knowing that it wasn't exactly ALL ORIGINAL. iIn the end i looked for a motherboard on EBAY and found a NEW OLD STOCK MOTHERBOARD with a good battery (still good now too after more than a year) You can still find these boards on EBAY if you are interested. Much better than soldering.

In any event, you should use a CMOS battery that was designed for a Thinkpad as it will already have leads attached to the battery. The CR2032 battery was used in CMOS batteries for the T2x series (among others) so they should be easy to find. Simply cut the connector off the battery; clip only one lead at a time to prevent an accidental short! Solder the red and black leads according to that photo. I'm assuming that whoever did that mod knew the correct polarity :) .
http://www.ebay.com/itm/5-BR1225-1VC-PANASONIC-12-5MM-COIN-BATTERY-W-LEGS-/220704359395

I have successfully re-celled a 701c battery. If the PCB has not terribly corroded, it's a straightforward operation. Simply open up the casing, cut off the old cells, clean everything up, solder in new cells, and done.
I simply bought a set of AA cells with solder tabs on ebay: http://www.ebay.com/itm/290535051997 The seller also has their own website if you prefer that. So far they seem to perform adequately.

i DO have NOS system boards, batteries (all dead, i'm sure) and NOS keyboards.. Bill Morrow, Sysop - forum.thinkpads.com

CMOS battery replacement info: http://forum.thinkpads.com/viewtopic.php?f=6&t=115043


Fixing the battery: http://www.conradshome.com/thinkpad/701/battery/