Here is a little function I wrote to capture just what you are looking for.
I used it to create an updateable table. You may have to tweek it a little
for you purposes. Sorry about the formatting on paste from notepad. :(

Ted White
Intelesoft

function TblRecordsOnClick()
{
 var tempText;
 var cellWidth;

 if (event.srcElement.tagName == "TD")
 {
  if (curRow != 0)
  {
   tempText = EditBox.value;
   tblRecords.rows(curRow).cells(curCol).innerHTML = "";
   tblRecords.rows(curRow).cells(curCol).innerText = tempText;
  }
  curRow = event.srcElement.parentElement.rowIndex;
  curCol = event.srcElement.cellIndex;
  tempText = tblRecords.rows(curRow).cells(curCol).innerText;
  cellWidth = tblHeader.rows(0).cells(curCol).style.width;
  tblRecords.rows(curRow).cells(curCol).innerText = "";
  tblRecords.rows(curRow).cells(curCol).insertAdjacentHTML("BeforeEnd",
"<INPUT ID='EditBox' TYPE='Text' VALUE='" + tempText + "' STYLE='width:" +
cellWidth + ";'>");
 }