Is there anyway I can incorporate a strobe function into my led flashlight?

I would like to be about to use the flashlight only as a strobe light. Is there a simple setup for that? The flashlight is a cheap 6 led with a rear push  on/off button. It is powered by 3 AAA battery in a housing that fits in the flashlight tube.

Pretty simple, if you can build the electronics to fit in the case ! Just use a 555 timer circuit and a transistor.,
Note, however, that a "real" motion-stopping strobe relies on an extremely bright but extremely brief flash. You aren't going to get that much brightness out of LEDs, so if you make the pulse too brief it's going to be very dim.
Weeeeeellll, if you DO pulse them you can seriously increase the forward current, up to, I would say, as a rule of thumb, about 10X their nominal current - for 1/10th of the time.

Ultimately, the die bonding wires fuse, so 10X is a rough idea, a proper datasheet will tell you,