Ok, I figured out a solution! This will set the focus of a specific row within a tablebox(). Basically, you just need to disable the standard scrolling associated with a tablebox(), then wrap that tablebox within a scrollbox(). Here's roughly how it's done:
//r10 is a report of a data table called dt10
//wrap the report tablebox in a scrollbox
sb10 = Scroll Box( size( 700, 400 ), r10 );
//disable the scrolling of the report tablebox
r10[Table Box( 1 )] << set selectable rows();
r10[Table Box( 1 )] << set scrollable( 0, 0 );
//find max hor and vert pixel range of scrollbox sb10
sb10max = sb10 << get scroll extents;
//now reference the vertical component of sb10max
//make a buttonbox and you can find key rows in tablebox
//and find their ratio of where they occur as row indices to nrows(dt10)
//then multiply them by sb10max and this will force the
//tablebox to scroll by the action of the buttonbox! woo-hoo!