I want to debug my project with OllyDbg. It's an BCB6 project.

Can OllyDbg use the .map file produced by BCB6?

I can import the .map file using MapConv.dll now.

Is it possible to load the .cpp source file into OllyDbg?

yes
if you had compiled it with debuginfo use ctrl+f5
if you dont have debuginfo
then you can load obj files also
use right click -->analyze -->scan object files
you can also use the implib scanner
see view menu