Inside the AEM ECU, you will find a 100 pin connector that is in between the main board and adapter board. At that connector, every single one of the AEM's inputs and outputs are available there. Some cutting and soldering will allow you to get extra I/O to the outside world. (This pinout is the same for EVERY Series 1 AEM ECU BTW)
The injector outputs on that connector are as follows:
Inj 1 - 89
Inj 2 - 87
Inj 3 - 85
Inj 4 - 98
Inj 5 - 100
Inj 6 - 99
Inj 7 - 92
Inj 8 - 91
Inj 9 - 94
Inj 10 - 93
The side of the board with all the components are the odd numbers pins and the other side are all the even ones. If you hold the board with the harness connector to the left and the component side facing you, the top is pin 1 and the bottom is 99. Sometimes the boards with have the pin values silk screened on, but not all.
With a little re-work, you should be able to have sequential injection. I would recommend using 18-20ga wire for an injector output rewire.