You can only hack PSP Mode by downloading one (which entails buying) of the Ninja releases from PSN once it's announced at wololo.net (you can get announcements early if you sign up on their forums) and installing an eCFW or VHBL, however I personally don't recommend it as you have to keep your PSVita out-of-date if you want the exploit to work, and that nullifies any benefits from PSN and PSPlus, which are a far better value as far as PSVita content is concerned. PSVita Mode is not hacked as of today.