theheroGAC has released version 2.24 of his TF-Card-Plugin-Tool. This update adds support for Vita firmwares 3.69 and 3.70. And I am happy to confirm that it works on 3.70.

Now we are all free to update to the latest firmware and still be able to take full advantage of all the benefits Trinity affords us. We can use TheFloW's Adrenaline on 3.70; we can use Xperi's USB video streaming plugin on 3.70; and now we can use theheroGAC's TF-Card-Plugin-Tool to switch back and forth between the official Vita memory card and the SD2Vita. And with the PSVimgTools Whitelist hack for the PSTV, there is nothing stopping us from playing all Vita, PSP and PSone games on a HDTV. Compatibility issues are now a thing of a past. Limited storage is now a thing of the past. Blacklisted games are no longer an issue. With this latest contribution to the Vita homebrew community, the PlayStation Vita and PlayStation TV have been completely unleashed!

Have fun. :D