After some days of trying and searching around 2 topics actually helped me to understand how it's done.
1. A full and easy guide
2. Some beautiful examples
The only thing you actually have to change is in Glitchys MES in Spell Swap in the 2nd step to save it as ".MPQ" and not as ".mpq" which is the default there.
As for the spell ID's i was trying to get the ID's from my combatlog...which is wrong... get the simple ID's from your abilities and the highest rank ofc from any site.
Anyway i've made 2 for shadowpriests 1 for spells & 1 for procs
1. Mind flay to Drain Soul - Rapidshare Link
2. Now it's the time -> Power Circle
Embrace of the Spider -> Fel Infusion
Shadowy Insight -> Arcane power
All in 1 here