No, unfortunately not. What you see is what you get in the application tray. They only allow you to rearrange the stock tabs (there may be a 3rd party program or you could root for more customization)
My workaround is to create a folder with the needed applications on the homescreen.
You can accomplish this by long pressing the home screen to add a new item. Tap the second tab on the bottom labeled 'apps', then select individually which applications you want to group together and they will be sent to the home screen. To start a folder simply long press one of the application shortcuts and drag it over top of one of the others and it will pop them together into a folder. Then drag all the other application shortcuts into that folder.
You will then have a more easily accessible and customized 'app tray' at your fingertips