As an Xperia Play user, I find that using the phone's gamepad shoulder buttons would be the best way to navigate between pages. I find every other set up to be less comfortable. However, there is no way for me to set the Next Page/Previous Page functions to these buttons. There is no option in Droid Comic Viewer to do so.
To apply to a wider range of users instead of just Xperia Play users, I suggest adding a key mapping feature where keys are mapped to functions. Currently, functions are set to keys. For an example, the user can set the "Back" button to navigate to the previous page or scroll down the current page. Key mapping would be the opposite, where the user is able to select a function, such as navigate to the next page, and input the button that would execute this function (in my case, I would love to set "Next Page" to Xperia Play's left shoulder button).