[Catalyst] rewrite or reload on YAML

[Wan]

I will run myapp on mod_perl or FastCGI, but I want to know how to
rewrite or reload my YAML file.

for example

# myapp has this line
$c->config->{SomeKey} = 'SomeValue';

.....

How can save this value to my YAML file, and how can I reload this value.
I don't want restart my web server. Before Catalyst I usually save the
values
to a file and reload the values myself.

I'm a beginner of YAML and Catalyst.

Thanks for any help!