I have successfully used the freeware product Type Light from here: http://cr8software.net/typelight.html to customize a font.
"To add a new node to the middle of a contour (PS or TT mode): Select one of the curve tools (corner curve, straight curve or straight corner), then move the mouse onto the curve until the cursor displays a small square next to it (meaning that you are on the contour). Press the left mouse button and the node will be inserted at that position."
Decompose a glyph: this is the 3rd "A" icon in the toolbar.
See also: http://fontforge.github.io/en-US/ - Open Source. Originally from Linux. Has a Windows download now. Not tried.
tags: font, type light