I like alphanumerical citations written as in alpha.bst style, with initials of authors and years, but I would like references to appear sorted as in plain.bst style. As an example, I prefer the order
[BN07] M. Baker and S. Norine (2007)...
[Blo07] S. Bloch (2007)...
to
[Blo07] S. Bloch (2007)...
[BN07] M. Baker and S. Norine (2007)...
Then I would like to know how to modify the *.bst file in order to get what I want.