Given that I have a pointer to a function (provided by dlsym() for example) and a linked list of typed arguments, how can I construct a C function call with those arguments?

Example:

struct param {
   enum type { INT32, INT64, STRING, BOOL } type;
   union { int i32; long long i64; char *str; bool b; } value;
   struct param *next;
 };
 int call_this(int (*function)(), struct param *args)
 { 
     int result;
     /* magic here  that calls function(), which has a prototype of
     f(int, long long, char *, bool); , when args consist of a linked list of
     INT32, INT64, STRING, BOOL types. */
     return result;
 }

The OS is Linux. I would like the solution to be portable across MIPS, PPC and x86 (all 32 bits) architecture, using GCC as the compiler.

Thanks!