The Bubble Plot uses a FrameBox() for the display, and the FrameBox() supports << Add Graphics Script, so you can pretty much do whatever you need. Below is a simple script that was produced by adding a script through the "Customize" capability.
names default to here(1);
dt=open("$SAMPLE_DATA/Air Traffic.jmp");
Bubble Plot(
X( :Latitude ),
Y( :Longitude ),
Time( :Time ),
Time Index( 26.7000000000001 ),
Title Position( 35.75, -22.75 ),
SendToReport(
Dispatch(
{},
"1",
ScaleBox,
{Format( "Latitude DDD", "PUNDIR", 16, 0 ), Min( -2.5 ), Max( 72.5 ),
Inc( 5 ), Minor Ticks( 1 )}
),
Dispatch(
{},
"2",
ScaleBox,
{Format( "Longitude DDD", "PUNDIR", 16, 0 ), Min( -179.486111111111 ),
Max( 5.51388888888889 ), Inc( 10 ), Minor Ticks( 1 )}
),
Dispatch(
{},
"Bubble Plot",
FrameBox,
{Add Graphics Script(
4,
Description( "" ),
Text(
Center Justified,
{Col Mean( :latitude ), Col Mean( :Longitude )},
"_text_"
)
), DispatchSeg(
TopSeg( 1 ),
{Set Script(
Text(
Center Justified,
{Col Mean( :latitude ), Col Mean( :Longitude )},
"_text_"
)
)}
)}
)
)
);
Jim