Hey! I've been thinking about trying something similar.

It's very possible to hook up an electric cooling fan to your Blaster, but it won't be a one-weekend job. My idea involves using a couple of small box fans, like those you find inside computers.
The problem with using one big 'radiator' fan is that the fan motor is simply too much for the Blaster's electrical system to handle. You would also need a relay to run the big fan, as well as the associated wiring and switches. This could all be done, but the Blaster would have to be fitted with a full-size battery, and the voltage regulator wired up in such a way as to charge this battery while the fan motor draws power from it. If a big fan were to be run directly off the current produced by the regulator, the motor would run poorly from a lack of steady input voltage, and you'd likely either burn up a regulator or lighting coil.
As for using 1 or 2 smaller fans, I bet these could be made to work with less effort. I'd still install a small, sealed battery under your seat, and tie it in with the voltage regulator. Why? Ever notice how your lights increase in intensity as the engine revs higher? This is because the lighting/charging circuit's voltage output is dependent on engine RPM. A cooling fan would not be very effective if it idled with the engine. By installing a battery, the fan would recieve a full 12 volts of power all the time, regardless of engine speed. As for the regulator? It could just charge the battery as needed. In theory, you could also isolate the lights from the rest of the Blaster's circuitry, running them off the same battery as the fan(s). The charging coil and regulator then just become the charging circuit for the battery.
I've never tried anything like this, but as long as low-wattage fans are used.... You still run a small risk of damaging something by experimenting, but, hey.... It might be worth a shot! Those small fans should work just fine with only basic wiring and a strategically-placed switch.