The type font I used is Lucida Console on the notepad program.  
This information will prove useful if nothing lines up properly in this tab.

Open G tuning: Low to high DGDGBD

Okay, so, skipping the intro and going straight to the riff . . .

      1  e  a  u  2ea  u     3 e a u4    e au     1  e a u 2 e a u 3 e a u 4 e au 
E  --/12-12-12-12-12--------0-0-3/5-----3-0----:----0-----0-----0-----0-----0---------------
B  --/12-12-12-12-12--------0-0-3/5-----3-0----:------0-----0-----0-----0-----3-------------
G  --/12-12-12-12-12--------0-0-3/5-----3-0----:-10-----9-----7-----5-----4-----------------
D  ---------------------------------------------:--------------------------------------------
A  ---------------------------------------------:--------------------------------------------
E  ---------------------------------------------:--------------------------------------------
     w/ slide                                      w/ pick and fingers

So, the first measure you use the slide, but the second measure you don't.  
However, I think he plays that second measure with his pick, index, and middle fingers.

Do this riff many times before going to the twelve bar blues section below.

      1e   a u   2e  a u   3e  a u  4 ea   u        Repeat x3    
E  ---0----x-x---x---x-x---x---x-x--x-0----0--:--------------------
B  ---3----x-x---5---x-x---6---x-x--5-3----3--:----------/---------
G  ---4----x-x---4---x-x---4---x-x--4-4----4--:-----*---/----------
D  -------------------------------------------:--------/---*-------
A  -------------------------------------------:-------/------------
E  -------------------------------------------:--------------------
                                                


     1e a  u   2  e  au  3e  au  4eau    1e  au2  e   au   3e  au  4eau 
E  --x--10-10--------------------------:-------------------------------------------------
B  --x--11-11--11-11-11--10--10--11----:-----11---11--11---10--10--10--------------------
G  --x--12-12--12-12-12--12--12--12----:-----12---12--12---12--12--12--------------------
D  -----10-10--10-10-10--10--10--10----:-10--10---10--10---10--10--10--------------------
A  ------------------------------------:-------------------------------------------------
E  ------------------------------------:-------------------------------------------------
Note: you could probably ignore the notes on the high E string in the measure above.  
I think Page hit those on accident, as I can't hear him hitting them in the rest of the song.
They did, however, provide me with the clue I needed to identify the correct chord inversion, 
which is why I put them in the tab.


      1e   a u   2e  a u   3e  a u  4 ea   u                             Repeat once    
E  ---0----x-x---x---x-x---x---x-x--x-0----0--:-------------------------------------------------------
B  ---3----x-x---5---x-x---6---x-x--5-3----3--:--------------------------------/----------------------
G  ---4----x-x---4---x-x---4---x-x--4-4----4--:---------------------------*---/-----------------------
D  -------------------------------------------:------------------------------/---*--------------------
A  -------------------------------------------:-----------------------------/-------------------------
E  -------------------------------------------:-------------------------------------------------------



     1e a  u   2  e  au  3e  au  4eau    1e   au2   e  au  3e    au   4e  au 
E  ------------------------------------:-----/-8----8--8---8------------------------------------
B  --x--13-13--13-13-13--12--12--13----:-----/-8----8--8---8------------------------------------
G  --x--14-14--14-14-14--14--14--14----:----sl-------------------0---/3--/3---------------------
D  -----12-12--12-12-12--12--12--12----:------------------------------sl---sl-------------------
A  ------------------------------------:--------------------------------------------------------
E  ------------------------------------:--------------------------------------------------------

       1e  au   2  e au  3 e au 4 e au    1e a  u  2e  au3e  au  4e  au 
E  --------0-------0-------0------0----:--------0------0---------0---0---------------------
B  ------------------------------------:---------------------------------------------------
G  ----0--------10---10--9---9--8---8--:--7--7-----7---------7-----------------------------
D  ------------------------------------:---------------------------------------------------
A  ------------------------------------:---------------------------------------------------
E  ------------------------------------:---------------------------------------------------

Alternate between the riff and the twelve bar blues section for the whole song.
There's some variations on what is written here, as Page would improvise a bit around 
the general idea for songs, especially an impromptu jam such as this one probably was.

My apologies if this comes out crooked or not lined up properly; this is my first time posting a tab.
I suggest copying and pasting to the Notepad program and deselecting the Word Wrap function under the Edit menu.
Please feel free to email me with any questions.
[email protected]