I used to have Flows; they were crappy compared to the current high-end Flow models, but I see that some of the basic difficulties remain. Here's another trick you might try if entry is difficult on the slopes and you don't feel like adjusting the straps (my son actually used this technique most of time): Kneel down and stick your boot into the binding as far as it will go (since the board's edge is digging into the snow, it can't slide while you're pushing with your foot), then reach back and raise and lock the highback. When you stand up, press down with your heel and your weight will cause the boot to squeeze down the last inch or so and pop into place securely. There's nothing subtle about this method, but it's fast and it works.
I use method that goes along the same school of thought as this. I don't bend down on my knees, but do dig my toe edge in. This is part of the learned techniques that you pick up over time. I do this little shimmy thing that gets my boots in.
But most of all, like I said, using the highbacks to aid in pushing your boot forward helps. I noticed that a lot of my friends trying out my Flows try to completely kick in and don't even attempt to use the high back to help. They think they have to get the boot all the way in before lifting the high back.