Mapping PPM Signals to Servo Values
int PPM_INPUT_PIN = TinyPpmReader.width_us(3); 


will save the result into variable PPM_INPUT_PIN, while 

val0 = analogRead(PPM_INPUT_PIN);


will save an analog reading results from PPM_INPUT_PIN channel into variable val0. This is (one of) your problem.
To map the PPM value, you can do:

#include &lt;TinyServo.h&gt;
#include &lt;TinyPinChange.h&gt;
#include &lt;TinyPpmReader.h&gt;
#include &lt;Rcul.h&gt;

int val0,                     // integer to store value
    mappedval0;               // integer to store mapped value;

const byte SERVOS = 1;                   // how many servos do you have? up to 5 on ATTiny85 and 8 on ATtiny84/2313
const byte servoPin[SERVOS] = { 0 }; // what pins are your servos on?
                                       // you have the option to give your servos nice names. 0 refers to the first servo pin above, 1 to the second, etc


#define PANSERVO 0
#define PPM_INPUT_PIN  2    &lt;--------- //define pin for ppm input


const int PPM_max_value = xxxxx; //put the max value of PPM reading result
const int PPM_min_value = yyyyy; //put the min value of PPM reading result


void setup()
{
  setupServos();
}


void loop() 
{ 
  val0 = TinyPpmReader.width_us(4);   //get PPM reading result from index 4
  mappedval0= map(val0, PPM_min_value, PPM_max_value, 0, 180);
    // scale it to use it with the servo (value between 0 and 180) 

  moveServo(PANSERVO, mappedval0);
  delay(5);                           // waits for the servo to get there 
}