It can be alot of trial and error .. I generally start with something close then edit it to suit my needs.
I did this one in a few minutes .. it probably isn't the most efficient way, but it is close ...
*EXLT, -- EX/LT ----/----LT/EX----/----LT/EX----/----LT/EX----/----LT/EX----/----LT/EX----/----
A,.2,-.4,["EX LT",standard,S=.1,R=0.0,X=-0.325,Y=-.05],-.2,.5,[TRACK1,ltypeshp.shx,s=.1,R=-45.0,x=-0.8],.1,[TRACK1,ltypeshp.shx,s=.1,R=-45.0,x=-.15],.1
You shouldn't have to make a shape as there is already a shape defined as TRACK1 in the ltypeshp.shx file, you only need to rotate it -45 degrees to make it look like what you want ...