Someone must have a use for this, as he does. As for converting that struct though, you could split it up into separate arguments; one for each variable in the struct.
Although, that is a pretty big struct... :-\ So, maybe no, heh.
Code:
typedef struct clientdata_s
{
vec3_t origin;
vec3_t velocity;
int viewmodel;
vec3_t punchangle;
int flags;
int waterlevel;
int watertype;
vec3_t view_ofs;
float health;
int bInDuck;
int weapons; // remove?
int flTimeStepSound;
int flDuckTime;
int flSwimTime;
int waterjumptime;
float maxspeed;
float fov;
int weaponanim;
int m_iId;
int ammo_shells;
int ammo_nails;
int ammo_cells;
int ammo_rockets;
float m_flNextAttack;
int tfstate;
int pushmsec;
int deadflag;
char physinfo[ MAX_PHYSINFO_STRING ];
// For mods
int iuser1;
int iuser2;
int iuser3;
int iuser4;
float fuser1;
float fuser2;
float fuser3;
float fuser4;
vec3_t vuser1;
vec3_t vuser2;
vec3_t vuser3;
vec3_t vuser4;
} clientdata_t;