In case anyone else comes across this, here is the code I wrote to use a Marker to control the Time Remap. This marker is on the layer you want to adjust but you could also link this to any marker in a project.
var mark = thisLayer.marker.key(1).time; //Marker location
var begin = 0; //Start point of your clip
var dur = 1.2; //Clip duration in seconds
linear(time, mark, mark+dur, startTime, dur);