Well, the simple thing to do if you don't want to interfere with stuff you might have already set up is to go to around line 167 and see something like this (it may be different, since if you have Serenade you must have taken it from the demo and not the txt):
0 => ["Vocab::item", 144, "$game_party.members.empty?", false, Scene_Item],
1 => ["Vocab::skill", 128, "$game_party.members.empty?", true, Scene_Skill],
2 => ["Vocab::equip", 51, "$game_party.members.empty?", true, Scene_Equip],
3 => ["Vocab::status", 137, "$game_party.members.empty?", true, Scene_Status],
4 => ["Vocab::save", 133, "$game_system.save_disabled", false, Scene_File,
"true, false, false"],
5 => ["Vocab::game_end", 179, -1, false, Scene_End]
Add in a new line:
0 => ["Vocab::item", 144, "$game_party.members.empty?", false, Scene_Item],
1 => ["Vocab::skill", 128, "$game_party.members.empty?", true, Scene_Skill],
2 => ["Vocab::equip", 51, "$game_party.members.empty?", true, Scene_Equip],
3 => ["Vocab::status", 137, "$game_party.members.empty?", true, Scene_Status],
4 => ["Vocab::save", 133, "$game_system.save_disabled", false, Scene_File,
"true, false, false"],
5 => ["Vocab::game_end", 179, -1, false, Scene_End],
6 => ["Distribution", 137, -1, true, Scene_Stat_Dist]
then go down to somewhere around line 194 and see:
FSCMS_COMMANDLIST = [0, 1, 2, 4, 5]
Put in
FSCMS_COMMANDLIST = [0, 1, 2, 6, 4, 5]
And you're done. In case you didn't follow it, I put the modified script into a text document and attached it, so you can just copy paste it directly. However, it is the same process everytime you want to add another script to the menu, so I suggest you learn it.
You might also want to go to line 655 of the Stat Distribution script and change:
$scene = Scene_Map.new
to:
$scene = Scene_Menu.new