No problem! Do the text the normal way, in black, then go to the contiguous selection tool and set "grow selection" in the tool options. Something like 4 pixels for thin outline, 10 for medium outline, etc. From the selection outline, you should be able to see about what it's going to look like.



Then, this is important: select> smooth



You can do this next part different ways, but I stay on the same layer and use the fill tool (set to fill entire selection), set the foreground color to white and (important!) change the blending mode (the pull-down next to the eraser button) to *multiply*. This adds a white outline to the black letters seamlessly.



Finally: filter> adjust> invert