Sealit Pen SUCKS! I suggest 3M's Primer 94 if you want your edges to stay down.
I found that it didn't do anything. And the pen tip dried out VERY fast! And frankly in the 170+ wraps I've done I've never once had to seal my overlaps/seams and if there was any doubt I used a little primer 94 on the edge of one panel and laid the next panel on top.
And to calm your confusion the Sealit Pen is meant to go ON TOP of your graphics not underneath. Basically to "seal" the edge of one seam to another. But it sucks - don't waste your money.
Haven't used the 3M edge sealer though - like I said - never really found a time to need it. I was given the Sealit pen by the boss and said "Try this out, I heard it's supposed to help with blah blah blah..." So I did. It was useless.