Apparently this is fixed in patch 1.2, I couldn't get it in my latest playthrough but in this video you can get it. Need to climb up and position in an angle, anyway the datapad's no big deal. Cam just watch it here.
They fixed a lot of exploits in 1.2, like using melee weapons to "climb" up a wall, using kerezenkov to get a huge burst of speed, sliding to avoid fall damage, etc.
But I managed to get the sword and the datapad during The Heist before you slid down the slope and all that. Had to jump in such a way that you are standing on top of the open door. Basically the issue is the distance V can reach to pick something up.
So it may sound stupid but have you all tried to crouch to enter? I tried that after jumping on the roof of the car a few times and it seems to work, you need to be at a certain angle to crouch in and it should work as you can see in the screenshot below: