You mean "homebrew", don't you??
but as of now, no, it isn't possible to hack your 520, although you can get it developer unlocked. This will enable you to side load apps. I'm not sure how it works. Why don't you search "developer unlock"ing on the forums??
If u already have microsoft sdk for windows phone u can dev unlock it using the windows phone developer registration,but u r only allowed to install 2 apps at the same time,to be able to have more dev apps at the sime u need to pay
If u already have microsoft sdk for windows phone u can dev unlock it using the windows phone developer registration,but u r only allowed to install 2 apps at the same time,to be able to have more dev apps at the sime u need to pay