Does it need to be a hover label? Or could you use the picture as the symbol in your graph? For example, using the Big Class Families sample dataset:

If you only want pictures for selected rows, you could select them and Name Selection in Column, then use that Column to create a Transform column, like this:
// Open Data Table: Big Class Families.jmp
// → Data Table( "Big Class Families" )
Open( "$SAMPLE_DATA/Big Class Families.jmp" );
// Name selection in column: Use Images
Data Table( "Big Class Families" ) << Clear Select <<
Select Rows( [1, 6, 14, 15, 16] ) <<
Name Selection in Column( Column Name( "Use Images" ), Selected( 1 ) );
Graph Builder(
Transform Column( "Transform[height]", Formula( :height * :Use Images ) ),
Size( 648, 551 ),
Show Control Panel( 0 ),
Variables(
X( :weight ),
Y( :height ),
Y( :"Transform[height]"n, Position( 1 ) )
),
Elements(
Points( X, Y( 1 ), Y( 2 ), Legend( 3 ) ),
Points( X, Y( 2 ), Legend( 5 ), Set Shape Column( :picture ) )
)
);
I included the script so you can see the results with one click, but this can all be done within Graph Builder with no scripting. The key functionalities are Transform Columns and Set Shape Column.