You need to describe what your problem is a little better if you want any help. I have no idea from looking at your pics what you are trying to accomplish.
You can, if you properly align the blue laser. Those blue lasers may have different beam specs than the green you have there though. For example, the greens usually have a much narrower beam at aperture than the blues.
if your going for a single colour in that projector, replacing the laser shouldn't be too difficult. Just get it lined up on that turning mirror and it should work fine. You will however need to make sure your blue laser can be modulated. Modulation is when the laser is turned off to break the "retrace" lines that will appear when the show is running if the laser is constantly on.
The blue laser in my RGB is powered by a "Flexmod P3" which is able to be modulated. (I'm replacing the bluray diode with a 445nm when I change out the blown red laser.