Transparent proxy authentication with pf

I'm under a corporate, squid proxy.

It is problematic to develop under this proxy since I have to setup the proxy details for every thing I use (for example, setting npm, or terminal http_proxy)

I am looking for a way to route all my traffic to squid proxy, so that I do not have to edit all my applications' proxy settings.

I found a short tutorial to do transparent proxying with squid here using pf. However, I am not familiar with pf.

This is the pf configuration that the tutorial says is needed:

int_if="gem0"
ext_if="kue0"

rdr on $int_if inet proto tcp from any to any port www -> 127.0.0.1 port 3128

pass in on $int_if inet proto tcp from any to 127.0.0.1 port 3128 keep state
pass out on $ext_if inet proto tcp from any to any port www keep state

However, the proxy I'm under has authentication required (username and password).

How do I setup my pf so that I can tunnel all my applications to use this proxy? If the config above is ideal, then how do I change it to accept my authentication details?