See this post for details and a link to the at2 file: Mod of the Mod.
Note that Lancer is currently very busy working on getting Decisive Campaigns 3 out the door. I expect that when that project is complete he may have time to revisit his excellent mod and update it properly.
Change your defaultmod.txt file (root folder of ATG) as follows to have a button to launch 1enhanced.at2 or simply launch it manually.
Advanced Tactics Gold
0
modgraphics
atgoldscenarios
sound
-
intro.ogg
12 <-- changed from 11 to 12
1,3,-465,568,Standard Random Game,13,generic.at2
1,3,-465,608,Alt Gfx Random Game,13,generic2.at2,noweather
1,3,-465,648,A New Dawn Random Game,13,anewdawn3.at2,nocrates
1,3,-465,688,Classic Random Game,11,classic.at2
1,3,-152,568,Load Saved Game,4,savedgames
1,3,-152,608,Install Zip/File,15,
1,3,-152,648,Editor,12,classic.at2
1,3,-152,688,Enhanced Mod Suite,13,1enhanced.at2,nocrates <-- add this line
1,3,160,568,Load Scenario,3,atgoldscenarios\
1,3,160,608,Credits,14,
1,3,160,648,Quit,5,
1,3,160,688,AdvancedTactics.org,6,http://www.advancedtactics.org