No I don't think you can do that. The leads are trimmed differently. Also, I think the led in the Photon 3 is soldered, making a nuisance.
I'm not sure what your end goal is. You want a white led in your Photon 2? That's easy, the P2 led is not soldered. Just put replace the green led with a white one. If you need a white led, PM me your address and I'll send you one. Or call Photon customer service and ask if you can buy a white led for a Photon 2 (slightly preferable to me sending you one, since theirs have gold plated leads). I asked them if I could buy a white led and they sent it for free, already plated, trimmed and formed for the Photon 2 (otherwise you have to trim and bend it yourself, no big deal).
If you're aiming for a P3 with a blue led, that's a bit harder, because of the soldering. I may have a blue one around here that I'd unload pretty cheap. I'm not crazy about the P3 either. I like the newer Freedom much better, and its led is not soldered so it's much easier to replace.
Or if you just want a P2-style light with a white led, I have tons of those so I'll drop one in the mail to you. Welcome to CPF. /ubbthreads/images/graemlins/wink.gif