I bought a "Braker Flasher Module" from:
http://autolumination.com/1156_1157.htm
I bought the Single Circuit and installed it on my Stella & my Scarabeo 250. You just cut one brake wire and hook it up "in-line". It flashes 10-20 times for 2 seconds, then stays solid as long has you hold the brake. It's the best mod I've done yet!
The modulator is ONLY $5.99 + $3 or $4 shipping. You must be using an LED light(s) as it won't work with standard bulbs.
Here are some pics of it installed on my stella brake light. I'll post some more pics (when I get them) of my Scarabeo install. It will be easier to see.
The blue and brown wires are coming from the modulator and it fit easily in my brake light housing as it's small and flat.
And I bought this LED light to go in my Stella brake light socket (1156 / Eagle 5). It's also from autolumination.com.