No it's totally not practical but I've started trying to do it. It's a whole task but I've done GF2 and a part of GF1. Here it is.

I have given the extra scenes a number as you can see (stuff beneath is copied from jgeoff site)

1901-1917
1>Searching for Vito (Ciccio's men looking for boy)
2>Fanucci Attacked (gets throad cut by punks)
3>Clemenza: "I'm my own boss" (added to cafe scene)
4>Playing The Flute (visit to the gunsmith)
5>Discussing Fanucci (additional Vito truck footage)

1917-1927
6>Reasoning with Signor Roberto (additional footage)
7>Don Vito Corleone (added footage of Roberto visiting Vito)
8>Introducing Hyman Roth (Hyman Suchowski)
9>Vito's Revenge (killing Ciccio's goons)

1945
10>The Death of Genco (in the hospital after the wedding)
11>A Gift from Woltz (his girl-friend Janie gets a pony)
12>Hagen Sees Janie (on his way out after dinner)
13>A Family Fight (Connie and Carlo argueing at Vito's)
14>Michael and Kay in Bed (in NY, pretending to be in New Hampshire)
15>The Don's Been Shot (Sonny gets a call)
16>Sonny Absorbs The News (added footage)
17>Michael Gets Involved (crucial footage!)
18>Planning Paulie's Death (Rocco makes his bones)
19>Clemenza Eats Lunch (while Paulie and Rocco wait in car)

Then If you want to see it in chronological order you have to watch it this way:

GF 2 (Disc 1): 1,2 (After 5 min and 15 seconds you must watch extra scene 1), 3, 8, 9 (47 min 17 seconds extra scene 2 followed directly by scene 3, (Next time I write this as 47:17 S2)), 15 (1:46:06 S4 followed by S5)
GF 2 (Disc 2): 2(10:00 S6 followed by S7 and 8) and scene 9 after 38:18.

After that you watch GF 2 Disc 1: 4,5,6,7,10,11,12,13,14, (Disc 2) 3,4,5,6,8,9,10,11,12,13,14

Pfff, that was GF2

GF 1(partly): 1,2,3(25:29 S10)(then when 3 ends you must look S11),4(30:49 S12 followed by S13),5 (after 5 you must look S14),6 (43:54 S15 followed by S16),7(50:48 S17)(53:09 S18)(54:02 S19).

Today I hope to finish GF1