You'll need WPE. I guess you have it.
1.Start WPE and Attach it to wow.exe
2.Open a filter and look below-
Changing packet on character creating
01-06= always variable
07-10= Name
11= After name always 00
12= Race
13= Class
14= 01-female 00-male
15= Skin color
16= Face
17= Hair style
18= Hair color
19= Markings & horn style & other
20= Always 00
3.Look the red one, Go to that 14 in the filter.
14
00 (00 For Male 01 For Female)
xx
Change it to something like
14
00
4F
4.Activate filter, Create character with 4 letters. Login!
Credits to Karol @ Deathsoft for this wonderfull hack. [GUIDE] Model/Skin Editing With WPE Pro - DeathSoft
THIS IS SERVER-SIDED SO EVERYONE CAN SEE YOU IN THAT MODEL YOU GET.