What Lassie? there are Seals in the centerboard wells? Oh no!

If you are talking about the Gaskets that are attached under the hulls... the way i do it is....
PREP IS EVERYTHING... remove ALL the old gasket and adhesive. ALL... (got it?). Lots of elbow grease and Goof Off (gunk cleaner avialable online or at walmart).. it takes me over an hour to clean the area (each)
then i use contact cement (as do everyone i know). First apply it on the cat then also on the gasket. let them both dry for 10-15 min (the can tells you a way to test for correct "dryness"). THen i re-apply a second coat on each.
Then press into place. YOU GOT 1 SHOT to get it right! if you put the gasket on.. and its wrong.. and you try to rip it off.... you will never get a good "seat". It may work for a while but it will not last as long as if you got it right the first time. I use painters tape to mark out the correct area.
It is much easier to do with the boat upside down... but getting your cat upside down isn't easy...
PS the gasket material i use is called Center Board Slot Tape and i get it from LayLine.com
PPS... since this section (Myster) is basically dead... you should probably post in the general forum or PM me.... if you need a faster responce.