As long as you know your stuff and you have a good portfolio that shows potential, and you have the attitude and willingness to learn a new app, you should be ok.
What you could do is download trial versions of max/xsi/maya and have atleast some experiences with them albeit very basic knowledge. Or perhaps watch free tutorials online so you get some ideas of them.
Also most companies that hire during full hectic productions usually don't have much time and so would prefer experienced people. The ideal company is one that invest in juniors and to join at the beginning of a project where there is time to learn their primary 3D app.
Good luck
(I wish some day Autodesk just consolidate them all in one app and we all work using the best features)