First you are going to want to open a new file, about 12"x3", 300 dpi and background transparent.
Next pick out a cursive font. I chose Beautiful ES to work with. If you don't remember or didn't see the post on fonts, check out "Eerie-sistable fonts". Open the font and minimize.
On your new 12"x3" file, type in the word(s) you want to add a tail to. Setting the size up high (you can always reduce the size later).
If you had your text selection as a vector, change the layer to a raster (Layers>convert to raster). The "n" curved up so I erased part of it to make the swirly tail more natural.
Click on the brush tool then go to View>Palettes>Brush Variance.
On the brush variance palette, click on the reset arrow at the bottom right. Set the size to fade out, uncheck scale and the fade rate is going to variable. You are just going to have to try it until you get the length you want. It goes up to 10000 pixels. Just remember your 12"x3" file is 3600 pixels wide.
Below are the settings I used for my brush. This probably won't be exactly what you need but it's a good starting point.
I copied my cheat into the Halloween file and opened a new layer above it. Choosing a contrasting color, I drew my swirly tail on the new layer. As you can see, even with a cheat I can't draw well.
Once that is finished I deleted my cheat layer, lowered the opacity on the tail layer and zoomed in close.
I moved the tail around until I liked how it merged with the "n" and erased those tail parts that were sticking out around the edge. Raise the opacity and do a control & a then control & f. This will let you see any floaties still left around.
Deselect, then either erase those areas or marquee around them and delete. Once you have gotten rid of all the floaties, chose your brush tool and reset your brush variance palette back to the default (the arrow on the bottom right) and close the palette. Once again control & a, control & f, control & shift & f on the tail layer. Selections>modify>expand (1). Set the brush to the same color as your word(s) and paint over the tail. Make any last minute erasures where the tail and character meet.
Now it is time to merge the layers. Layers>merge>merge visible.
And once more, control & a, control & f, control & shift & f. Flood fill with your favorite glitter.
Just an observation, it helps to have a graphic tablet and pen.
Lyrics "What's This?" from A Nightmare Before Christmas; Fonts: Beautiful ES