typedef struct
{
VECTOR* Pos;
char* File;
} Enemy;

void CreateEnemy(Enemy* Definition)
{
ent_create(Definition.File, Definition.Pos, NULL);

...
}

void main()
{
Enemy* MyEnemy = malloc(sizeof(Enemy));
VECTOR* MyPos = malloc(sizeof(VECTOR));

MyPos.x=0;
MyPos.y=0;
MyPos.z=100;

MyEnemy.File = (char*)"BadBoy";
MyEnemy.Pos = MyPos;

CreateEnemy(MyEnemy);
}