Here is a simple example
names default to here(1);
dt=
// Open Data Table: Fish Patty.jmp
// → Data Table( "Fish Patty" )
Open( "$SAMPLE_DATA/Fish Patty.jmp" );
Ternary Plot(
X( :Mullet, :Sheepshead, :Croaker ),
Contour Formula( :Predicted Rating )
);
current report()[NumberColEditBox(2)]<<set({55});
To get the path to the NumberColEditBox, right click on the graph and select Show Properties, then click on the NumberColEditBox and look at the Box Path

Jim