SamRock
You just need to loop over all the isometric objects a find the x and y extreme positions. The scroll clamping assumes the iso objects cover more than the screen, so it uses half the screen size (320,240 in this case) to make scrolling stop at the edge.
global number boundleft= 99999
global number boundright= -99999
global number boundtop= 99999
global number boundbottom= -99999
start of layout
for each sprite
--- set boundleft to min(boundleft , sprite.bboxleft)
--- set boundright to max(boundright , sprite.bboxright)
--- set boundtop to min(boundtop , sprite.bboxtop)
--- set boundbottom to max(boundbottom , sprite.bboxbottom)
every tick
--- scroll to (clamp(scrollx, boundleft+320, boundright-320), clamp(scrolly, boundtop+240, boundbottom-240))