just go to redsaiyan.net and go to esf beta's section and download and unzip:
Great Saiyaman By AznDragon and unzip to:
C:\Sierra\Half-Life\esforces\models\player\gohan
Then unzip it AGAIN to:
C:\Sierra\Half-Life\esforces\models\player\gohanssj
then get:
Adult Gohan Sound Pack and unzip to:
C:\Sierra\Half-Life\esforces\sound\player\gohan
perfect comvination, total you have an adult sounding saiyaman with a wiked cool dew rag
hope you like