The timer is wired between the incoming power supply switch and the rest of the electrics on the boiler, it is pretty involved as it has 4 wires and they tie in at junction box by the solenoid with many others. You will need a length of BX with three wires, red, black and white. Shoot me your Email address and if I can scan it, I can send you the drawing and instructions from the Axeman manual.
EDIT: If you already have a 3 wire pigtail from your old timer, this is how it goes. The two black wires are to the timer motor, this needs to run all the time when the boiler is powered. The 2 red wires are the timer's switch to fire her. Take one of each red and black and connect them to the incoming black wire, that line should be feeding power when the boiler switch is on. The other black wire connects to the incoming white wire. That is the ground leg, now your timer should run. The other red wire connects to the incoming red, this should power your stoker at connection #2 in the junction box (the pump, stoker motor and aquastat are fed at this connection, their other wire being ground).