For me personally, I'm not able to move around much but I do live in London where there is a pretty active tech scene. Here's how I did it:
* Let x be the technology you want to work with professionally.
* Spend roughly a year of occasional unfocused off-time building little side projects with x. You can do it faster if you have more drive than me.
* Put those side projects on your github profile or anywhere people can see them.
* Apply to companies that work with x, whether or not they say they are hiring, or take experienced hires from other technologies. Send your github profile along with the application. Preferably go via a connection, but this is not required.
* In the interview/application process, demonstrate strong, language-agnostic technical skills along with some fundamental knowledge/realisations specific to technology x.
* Let x be the technology you want to work with professionally.
* Spend roughly a year of occasional unfocused off-time building little side projects with x. You can do it faster if you have more drive than me.
* Put those side projects on your github profile or anywhere people can see them.
* Apply to companies that work with x, whether or not they say they are hiring, or take experienced hires from other technologies. Send your github profile along with the application. Preferably go via a connection, but this is not required.
* In the interview/application process, demonstrate strong, language-agnostic technical skills along with some fundamental knowledge/realisations specific to technology x.
YMMV.