Set the you pointer yourself to the explosive, then call detonate_ent(). Something like this should work:

Code:
void trigger_explo(ENTITY* explosive) // Will set the Flag of the saved entity to 1
{
   wait(1); // This is important as it returns to the caller, and gives us the chance to alter the you pointer opaque to the caller but visible to our callees

   you = explosive;
   detonate_ent();
}

Shitlord by trade and passion. Graphics programmer at Laminar Research.
I write blog posts at feresignum.com