Dilation of Specific points

I have a binary zero matrix form of an image.Now I wonder,how to perform dilation morphological operation only on certain locations(to be read from a 2D array) so that the locations would likely turn as disk shapes (using strel('disk',r) function) having value as 1's and rest of the part as 0's;

[KSSV]

Use imcrop for the region of interest..extract the locations also...do what you want..and replace it back to the original matrix.