Any Thunderbird/Firefox geeks reading this?

I've spent more than an hour trying to find the answer to this so I've decided to toss the question here in the vague hope that someone will read it and have the answer.

Is there a way to make Thunderbird (NOT the default email client) open URLs in Firefox (NOT the default browser)? If Firefox was the default browser this would not be a problem, but because this is not my PC and my brother is not at all computer savvy (and has no interest in becoming so) changing the default browser to Firefox from IE is not an option.

I'm frankly amazed that I could not find a setting in Thunderbird where you can specify what browser to use. I even went poking in the advanced settings of the prefs.js file. If there's an entry I could put in a user.js file to change the browser I haven't found any hint of it anywhere (in fact all I can find about editing the user.js file is where it should be located and that it doesn't exist by default.)

So, anyone have a nice site with a rundown of what could be put in that user.js file?

Edit to add:

I have found a list of preferences to work with. Based on what I see here, and on a site about integrating Thunderbird and Firefox on *nix, I thought I would have it solved with these six entries in my user.js file:

user_pref("network.protocol-handler.external.ftp",true);
user_pref("network.protocol-handler.external.http",true);
user_pref("network.protocol-handler.external.https",true);
user_pref("network.protocol-handler.app.ftp","C:\\Program Files\\Mozilla Firefox\\firefox.exe");
user_pref("network.protocol-handler.app.http","C:\\Program Files\\Mozilla Firefox\\firefox.exe");
user_pref("network.protocol-handler.app.https","C:\\Program Files\\Mozilla Firefox\\firefox.exe");

It still doesn't work (even though all of these show up in about:config and look correct.) Am I missing a typo or another setting that I need to tweak or something?

Tried adding the following, no effect:

user_pref("network.protocols.useSystemDefaults",false);

When it rains...

As if I needed another hassle....

I just found out that my domain host will cease all services October 1st. This means I will have no host for tephras.com, no mail, no website.

I'm not in a good position to look for a hosting service, let alone afford one, so this was just the sort of news I did not need to get while sitting 1000 miles from home waiting for mom to have a cancerous mass removed from her breast.

So far I have had 1and1 recommended by my erstwhile host. I'm admittedly spoiled by him, I was free to install what I liked and was given a lot of permissions on his server, so the hosting services are all both foreign in design and rather restrictive in practice.

I most likely will not be maintaining my PSP related site, the bandwidth and storage is too great. I don't want to lose my domain since I'd like to avoid having to change email addresses (the very thought of hunting down every site and person to update that is shudder inducing) and it's paid until next July.

This is pretty much the last straw for today. I'm going off to have a cry, if I can do that without someone demanding my time and attention yet again.