I just went for the standard - "lick-your-finger-and-smooth-it-out" approach... The seams are readily apparent, but more attractive than seam tape.
Now - if you really want to pull off the texturing...
Go to a hobby store and buy a jar of liquid latex rubber. Pick a nice out-of-the-way spot of ensolite (just in event of problems), spray it with non-stick spray and start painting
on the liquid rubber. Keep on going layer-after-layer until you build up a fairly substantial coating. Finally, peel it off and glue it to a rounded piece of wood that you can roll over the caulking after applying it.
Now *** I HAVE NOT TRIED THIS ***, but it should work. Undoubtedly the pattern maker will need to be coated either with water or non-stick spray before use (TEST!!!), but should do a nice job of replicating the surface texture of ensolite and blend in the seams seamlessly. :)