(Incidentally having now refreshed my mind as to how MS works BC is far simpler!)
(and as we now have postcode search I can at last leave MS behind :p)
OK, got it sorted now and can see why you're trying to use the arrow tool as that's what's needed in Mapsource.
Try this so you can see how it works in BC. Click on the route tool (same icon as in MS). Close the box that pops up and just click on the map to select a start point and again to select an end point. BC will now calculate the route based on the activity profile you've set. Now select the insert tool and hover it between the start and end points until you see a rather thick black line appear between the start and finish point. Left click the mouse and release. You'll now be able to drag the line to where you want and then left click. The route will now be recalculated using where you clicked as a via point. Add more points as required. Right click when you've finished to exit.
Hope that helps.
(Incidentally having now refreshed my mind as to how MS works BC is far simpler!)
I'm sure you'll be uninstalling it then :p
Mapsource starts instantly - no "database" to load every time. :p