"Diagonal" cells - text-wrapping question

Hi. I'm doing a tricky poor-man's-Illustrator project with Excel
2007. I'm trying to create the impression of a large cell that's been
split in half diagonally (with a diagonal ascending from bottom left
to top right). I've created a 2 x 2 grid of cells and put a diagonal
border through the lower left and top right cells and removed the
vertical, internal borders. Looks great so far. In addition, I'd
like to place text in the upper left and lower right cells. Ideally,
this text would be wider than the upper left or lower right cell and
would flow over into the adjacent cell, but not so far as to impinge
on the diagonal border. This seems to work if I only add one line of
text - but if I include an ALT-ENTER in either cell, in order to add a
second line of text, Excel seems to automatically change the
formatting of that cell to "Wrap Text". Is there a workaround? I
hope this question is clear, it's a bit murky...

Thanks very much.