If you think about doing this with JSL there are several ways.
For example, you could simply loop over the columns and conditionally replace cells
dt = Data Table("test.jmp");
For(i = 8, i <= N Col(dt), i++,
ur = dt << get rows where(Column(dt, i)[] > 0.5);
lr = dt << get rows where(Column(dt, i)[] < -0.5);
Column(dt, i)[ur] = 5;
Column(dt, i)[lr] = -5;
);
An alternative (JMP 13) is to work with data tables as matrices using subscripts. The syntax also supports assignment, i.e. replacement of cell values. Here's an example:
dt = Data Table("test.jmp");
t = 0.5; // Treshold value
c = 5; // Ceiling value
nr = N Row(dt);
nc = N Col(dt);
M = dt[1 :: nr, 8 :: nc];// Matrix with all cells from col 8 to end of table
U = M <= t; // Below upper limit?
L = M >= -t; // Above lower limit?
//Assign treshold values to data table
dt[1 :: nr, 8 :: nc] = M :* (U & L) + c * (!U - !L);