Yes. Just use the #at parameter. You can see all available options, just look in Controls.sc. You can also add your own.
eg.
...
(case #title
++paramCnt
(send hDialog:text(params[paramCnt]))
)
(case #at
= diagX params[++paramCnt]
= diagY params[++paramCnt]
)
(case #draw
Animate(
(send gCast:elements)
0
)
)
...