I don't know what Seaview color chart you're referring to or which particular Seaview you're building. As far as the exterior goes, the movie and 1st season and all 4' and 17' Seaviews are pretty basic, a dark grey over a light grey so light that it's almost white. According to people who have studied the miniatures, the colors could be:
Movie Seaviews
Topside: dark grey. FS 36300 is perfect, a close mix would be 50% light ghost grey FS36375 and 50% FS 36320
Bottom: an extremely pale grey that looks white compared to anything else, maybe a mix of JA Army grey FS35630 and Camo grey FS36622.
First season Seaviews
Topside: Dark grey FS 36118, close match Tamiya AS 10, RAF Ocean Grey
Bottom: light grey green, not quite green enough but close is Tamiya AS 16
From the few pictures I've seen, all of the 1st season miniatures were painted to match each other, as were all the movie miniatures.
For the 2nd season onwards, the 8' hero miniature (and possibly only the 8' - the 17' shows no signs of this paint scheme and no late 4's have been color documented) was painted a complex scheme that is authoritatively detailed in this thread:
http://www.hobbytalk.com/bbs1/showthread.php?t=320432&highlight=seaview