Select the maintenance function
Select "change cartridge"
Press the "Colour" button
This will move the cartridges out of the way of the rest pad and make it easy to move.
Remove the power cord from the printer without turning off the printer (ie: just pull out the cord, don't turn it off on the panel)
Gently ease the printhead unit over to the far left of the printer out of the way

Once you've done that you should see this sort of picture (minus the continuous ink supply tubing)

IMG: http://www.continuousink.info/forum/gallery2.php?g2_itemId=160

Now at this point you're pretty much on your own as to whether you try and detach the clip and seperate the tubes or go ahead and snip/cut the tubing as I've done...

If you manage to detach the clip then you just need to skip the clipping/cutting part below and continue the rest of the instructions.