I probably shouldn't be answering this as I don't know if the signature will show up in the three above, but I do know it will show up in scripts using the following method. I think it will do all.
Anyway, go to Administrative Options (CTRL + A) from the main screen and select yourself in the User Account window. Once your name is selected, click on the Browse button in the middle right. You can then browse to your transparent signature. Once the signature is saved to the chart, it will be stored in the ___Data001 folder in the AC folder. Getting it to size correctly can be a bit tricky.
HTH.
