Before starting on this, let me say that any custom detailing project will take a certain amount of kit-bashing skills, tools (drill bits, files, etc), and patience.  My goal here is to do the best I can to point you in the right direction.  If you look at a number of steam locomotive pictures, you will notice that almost every type of steamer produced had some sort of side piping on the engineer's (righthand) side of the loco.  You will find this on the small up to very large locomotives.  One way to make your model appear more prototypical is to add this piping to that area.  You can either make the piping unit yourself if you are comfortable with a soldering torch and brass material, or you can purchase a unit custom-made for your model from Yardbird Trains.  Below, I have outlined the basic procedure that I use when piping a locomotive model.

There are basically two ways to mount the piping unit.   One is to bend the pipe hangers at a right angle and glue in place under the walk way, the second is to cut slots in the walkway and slip each hanger into the corresponding slot.   If you choose to glue the brackets under the walk way, let me suggest that you rough up the brass brackets and walkway area with fine sandpaper prior to applying the glue.  This will improve the adhesion greatly.  Although it is a bit trickier to do, I use the cut-in method to make sure the unit is fastened securely.   To do this you will need to line up the piping unit to the loco for careful marking of the hangers on the walkway (Fig.1).   Next, using a razor saw, make a small cut the width of the hanger (Fig.2).   Measure up the unit several times while marking the next cuts so they will line up correctly with the hangers.   Any strain one way or another from incorrect spacing may result in the piping unit appearing bent, so take your time and cut carefully.   After all cuts are complete, test your unit out to see where the cab hanger will mount.   You may have to adjust the hangers somewhat to get the desired results.   When the unit is ready to mount, bend the pipes behind the cab at a right angle and let it run under the back of the cab.   You may cut off any excess you desire to from that area.   Make sure there is ample room in the front part of the unit as well.   When all looks like a good fit, place some superglue gel on each slot and on the hanger that goes inside the cab and fit in place (Fig.3).  Adjust the piping unit and let it set up.   After the glue is set hard, trim the ends with nippers and file smooth with the top of the walk way.  You may need to use model putty or even a small amount of glue gel to fill any voids that may show.  If so, let that dry thoroughly and file or sand smooth.  I always brush the new pieces with alcohol to remove any oils before painting.