Our adhesion molecule immunology lab stains for E selectin frequently,
P selectin they do not do.

They do frozen sections only, acetone fix 4C, 10 min, block with 
normal serum blocker 30 min, antibody 30 min  F(ab')2 frag secondary 1:250
30 min, Strepavidin HRP 1:500 20 min, AEC as chromogen, counterstain with
hematoxylin 10 dips or so.

The staining is never terribly bright, a bit weak would be a better word, with
these frozens.  However, you may want to try a metal enhanced DAB, 
Pierce has one that is very sensitive for weakly staining antibodies, or
the new Vector NovaRed, 5 times more sensitive than AEC, but a permanent
red end product (can be dehydrated, etc) to replace AEC.  

Their experience with P selectin was having seen it, and it looks like it 
worked well in the hands of those who performed the work.

Hope this helps
Gayle Callis