How do I map a local path to a drive letter in Windows 7?

If it is only local what you need, try subst.

subst u: C:\cygwin\home\bob\code\

Use vSubst. It is like the subst command line tool, but it has a UI and is persistent.

When you map drives they must be mapped to a SHARED network folder. You are trying to map to a local path, it won't work. Instead try sharing the Code folder then use this:

net use u: \\yourpcname\code /p:yes