This is a guide i wrote while back for Mangos, here ya go :
as for making them, two tables need attention
areatrigger_template
gameobject_template
first open table areatrigger_template
add a new table, give it a id #
example # 200000
you want your destination, so you fill in the following tables :
target_map
target_position_x
target_position_y
target_position_z
target_orientation
to get these cords, go anywhere in game
type .gps
and you'll get the info
then goto gameobject_template
and add a new entry
example 500000
entry - 500000
type - 27 (so you can access the portal with a right click)
displayId - 7186 (im just using the orb of translocation model, but you can use pretty much any model)
name - name of the portal
flags - 64 (make sure the flag is 64)
sound0 - 200000 (this is where you put in the area_trigger id #)
and there you have it, then you would spawn the game object :
.addgo 500000 (or whatever # you gave it in the gameobject_template)
(mangos)