Btw. saving a pointer in an integer variable will most likely not work. (JustSid just informed me that it is perfectly fine to use ints) You can however save them in vars, for instance as follows:

entity-skills are a var skill[100] array, thus writing
my.skill70 = ent_create(...);
and
my.skill71 = pan_create(...);
or
PANEL* pnl_tmp = pan_create(...);
my.skill71 = pnl_tmp;
is perfectly fine. You can then later retrieve the pointer by a simple cast:
((ENTITY*)my.skill70).x = 10;
or handier as
you = (ENTITY*)my.skill70;
pnl_tmp = (PANEL*)my.skill71;

The last two typecasts should not be necessary (you = my.skill70; should work, too) but I like to do it that way.