This only applies to the command line as near as I can tell so not relevant to my problem...

Indeed. Your example only shows that "cd" doesn't accept "/" as a separator. You'll find the same for most of MS's command-line tools because they use "/" to mark options. However, if it's quoted...

C:\>cd "c:/temp"

C:\Temp>
[download]

Update: Actually, it works unquoted for me too.

C:\>cd c:/temp

C:\Temp>
[download]

Even if the slash is the first character

C:\>cd /temp

C:\Temp>
[download]