[5v0]---+-------+--------------------------------[5v0]
        |       |
        |       | ,------------------(4)---------[GPIO-D7]
        |       | | ,----------------(3)---------[GPIO-D2]
        |       | | | ,--------------(2)---------[GPIO-D1]
        |       | | | | ,------------(1)---------[GPIO-D0]
        |       | | | | |
        |    .--|-|-|-|-|--.
        |     \ 5 4 3 2 1 / DB9/1
        |      \ 9 8 7 6 /
        |       `|-|-|-|'
        |        | | | |
        |        | | +-}------------(Clk)--------[GPIO-D8]
        |        | | | |      R16
        |        | | | `-----^v^v^---+-------+---[GPIO-A6]
       (5)       | | |               |       |
        |        `-}-}-------^v^v^---'       >
        |          | |        R19            < R1G
        |  .--(8)--+ |                       >
        |  |       | |        R29            |
        |  |     ,-}-}-------^v^v^---+---+---{---[GPIO-A5]
        |  |     | | |               |   |   |
        |  |     | | | ,-----^v^v^---'   |   |
        |  |     | | | |      R26        |   |
        |  |     | | | |                 |   |
        |  |    ,|-|-|-|.                >   |
        |  |   / 9 8 7 6 \           R2G <   |
        |  |  / 5 4 3 2 1 \ DB9/2        >   |
        |  | '--|-|-|-|-|--`             |   |
        |  |    | | | | |                |   |
        `--}----' | | | `---------(1)----{---{---[GPIO-D9]
           |      | | `-----------(2)----{---{---[GPIO-D10]
           |      | `-------------(3)----{---{---[GPIO-D11]
           |      `---------------(4)----{---{---[GPIO-D12]
           |                             |   |
[Gnd]------+-----------------------------+---+---[Gnd]

Resistors: Rxy ->  x -> Controller number
                   y -> Pin Number / Ground

RxG == Rx9 == 10K
       Rx6 == 6.8K  (~70.2% of Rx9)

Either download the source from here, or github (probably Github, as that will get realtime updates)

Place the code in : /path/to/.../digistump-avr/libraries/MegaUSB

Restart your Arduino IDE

Select Mega2USB from the examples menu