There's no way to run Vita ISOs yet; the Vita hasn't been cracked that much.
Also, Vita games aren't in a specific image format. They are just purely made up of encrypted files and directories.
However, despite us now being able to dump and decrypt those Vita games/apps since last month, there is still no solution to place the games back onto the system without all the game files probably being resigned and encrypted with the PFS protection.
So Vita romhacking is still a no-no at the moment. :/