Hi there mate! I'm using Lumia 540 too. Yes, you can get the unofficial release of Windows 10 through the Insider Program. Options are: Slow Ring and Fast Ring (recommended). But please remember that Windows 10 has still a lot of bugs that may affect your everyday use. You may want to wait for the OFFICIAL release of Window 10 later this year that can guarantee you smooth experience.
Hey mate I'm using Lumia 540..what if I install the insider windows 10...will it cause any damage?? Like low battery backup ..slow app openings??or something like that?. ...and when will Microsoft officially release windows 10 for Lumia 540?..plz help me out with this..