gistfile1.scala

// pseudo-code mixing quasiquotes with 2.10 syntax, don't worry ;)

Macros.doit( "a" -> ("b", "c"), "a1" -> ("b1", "c1") )

object Macros {
  def doit(xs: Any*) = macro doitImpl
  def doitImpl(c: Context)(xs: c.Expr[Any]*) = {
    import c.universe._

    val fields = xs.toList map {
      case q"${_}(${Literal(Constant(name: String))}).->[${_}]($value)" =>
         q"""
           val ${name} = functionDoingSomething(.. $valueConvertedToVarArgs) 
          /* inspects $value, verifies it's tupleX, converts it into a varargs */
         """
    }

    // use fields in some generated code...
  }
}

You can both match and splice with "..$". So by writing (..$value) or (..$args) in the pattern, you'll be able to capture a list of trees at once. Then you can verify its length and splice the list back into the result using (..$args). Please let me know if something doesn't work. (Probably that'd be better to do via twitter, since I usually don't get notifications about gist comments).