Try this if the surface you want to get on to is shoulder high or above
that.

Find a piling or other vertical support below the pier surface. Double a
length of line and make a rolling hitch on the vertical support as high as
you can reach. If there is a bollard, cleat, etc on the dock surface that
you can reach while seated, use that.

Then, take the two bitter ends and lead them fore and aft respectively
making them off to deck fittings or grab-lines on the outboard side of the
kayak.

If the kayak moving horizontally is a problem, take another piece of line
and run it from your inboard (dockside) grab-line around the piling/support
and back to your grabline.

These two methods used singley or in combination provide a more stable
platform for entering and exiting. Judiscious use of slip hitches enable you
to easily untie and recover the steadying lines.