Exclamation [Q] Add an application to start up - custom rom

Im working on my own ROM for Oneplusone

I need to an application to the start up. I searched around and every thing points to using start-up managers off playstore but that is not gonna work for this requirement

What file do i need to edit ? if anyone can nudge me in the right direction i would really appropriate it

Thank you for your time
Current
One Plus One - 64GB - Daily Driver


 

History so far

Nokia 1100 - Have no idea where it is | Nokia N95 - SOLD | Nokia 5800 - backup | HTC HD 2 Leo - SOLD | Inspire 4G-SOLD | HTC Desire HD - SOLD | Iphone 4 - Have no idea where it is | Samsung Galaxy S 2 - SOLD | Samsung Galaxy S 3 - SOLD | Lumia 900 - Lost | Nexus 4 - Broken | Nexus 5 - SOLD