Genesis to RGB (scart)

first of all, swap the pins around on the gamesx picture.. i.e. the ones on the left are actually on the right, and vice versa.

second, you just wire it up 1:1 to the scart plug (the "in" pins, not the "out" pins, and you usually only need 1 GND), where +5V go to pins 8 and 16 of the scart plug.
I checked the layout from gamesx on my original scart cable and it seems that the 5v and Sync pin are switched in the picture, 5V should be on pin 1 and Sync on pin 5 (male connector). Here the layout from my cable.

7 R -> 15

3 G -> 11

8 B -> 7

6 audio -> 2 and 6

5 sync -> 16

2 comp. video -> 20

4 ground -> 18 (or 4,5,9,13,17)

1 5V -> 8

The 5V is for switching your tv in RGB mode.
no, they aren't switched. I know for certain, since that sync pin is required for 32x to work properly, and had to add that line to my adapter cable later manually.
Arakon, Mikes picture is exactly what I wrote.

The sync is on pin 5 of the male connector (gamesx pic / pin 4 - female mikes pic). And the unused pin 7 in Mikes picture (pin 1 gamesx) is the switching voltage.
pin 4 in mike's pic/pin 5 gamesx pic is blanking, which is 5V, NOT a sync signal.

the pin 7 in mike's pic/pin 1 in gamesx pic is not needed for genesis, but is the sync signal for the 32X.