I cant see any reason why its would be a difficult conversion,
entity to struct that is. But then again, Ive had a lot of practice...
Basically, do the same as the other thread says, just replace ent_create with sys_malloc.
player.skill37 = sys_malloc(sizeof(INFO));
or
player.info = sys_malloc(sizeof(INFO));
//remember sys_malloc does NOT fill the values with zero's)
Then when you want to access the info-data, use the following.
INFO* temp_info = (INFO*)player->info;
var temp_health = temp_info.HEALTH;
Or, if you want to get really tricky...
var temp_health = ((INFO*)player->info).HEALTH;
Best of luck...