Shoutbox

I know that msn! has/had this function, to join chat lines of one user together.
For better demostration:

Glavic says:
1
Glavic says:
2
Glavic says:
3
Test says:
A
Test says:
B
Glavic says:
4
Glavic says:
5

this function joines lines toggether like >

Glavic says:
1
2
3
Test says:
A
B
Glavic says:
4
5

I cant find where to turn this on.