I have taken some photos (as much for my reference) and can certainly provide a parts list and some guidance on things I have learned.
Here is a starter for those who want to jump straight in:
sata to ide adaptor - http://linitx.com/viewproduct.php?prodid=11623
You can get some of ebay which are less than the £11 here, but I had trouble with them either not looking like their photos or not being compatible with 1TB drives.
1TB drive - Samsung SpinPoint F1 HD103UJ 1TB Hard Drive SATAII *32MB Cache* (£71 from ebuyer)
As space is tight you will also need some downward facing connectors for power (I got a molex to twin SATA power cable and used one of the legs to power the adaptor) and SATA for data.
Here are some key points that might help:
1) Some SATA-IDE adaptors have difficulty auto-negotiating down to 1.5. The Samsung drive I used had a jumper setting which forced the speed down.
2) The adaptor I used is designed for plugging into a motherboard. In order to connect it to the LS2 cable I used an IDE genderchanger and some lengths of wire.....I will explain more. You can't just use an IDE gender changer as the top and bottom pins will be tranposed (trust me). I used the gender changer to connect the top pins to the bottom pins then used lengths of wire to connect the bottom to the top. Some photos will help with this. Another way to do this might be to use a short IDE cable and two gender changes to move top to bottom and back to top again.
3) I used the double flash technique to format the drive and install Freelink. Double press the reset button to put the box into EM mode. Use the firmare upgrade tool to locate and start the firmware upload. It will fail the first time around as the drive is first formatting. To format the 1TB drive by the LS took about 2.5 hours. You know when it is completed as pressing the search button on the fireware upgrade tool finds the LS again. A second attempt at upgrading the firmware should work. I played about with repartitioning the drive with Knoppix but kept on having problems (each time a different one) - and yes I did use the fix_ext2_magic tool. So I ended up leaving alone.
4) I had problems installing SAMBA etc as versions appear to have changed since most of the guides on this website (and since I last moved a box to Freelink). I changed /etc/apt/sources.list to point to etch. This meant that Samba 3 was installed so my old smb.conf was wrong and needed updating.
I still haven't got the case closed but I am hoping there is enough space to do this.
The drive has been running out of the box for over a week and I have copied over about 100GB including some videos. The videos play fine on the PS3 with Twonky so the speed doesn't appear to be too bad. I am considering this as a short term solution as my "main" server and a long term solution as a backup server - as soon as the Buffalo Linkstation Pro XHL is available in the UK (at a sensible price) I think I will be upgrading.
Let me know if anyone needs to know any specifics, but hopefully this is of some help.