I'm in the same situation as you. I tried using my router with my Dad's laptop's satellite card... = epic fail. The connection goes in and out so much....
You probably already know this but you can play some games with dial-up. My friend would say all but only about 70% of games. I don't know how well Brawl would play on it; probably best with a friend 1 on 1.
Cuz I tried playing Mario Strikers Charged Football online and it's not anything like the other games is actually freezes so it's like stop-go-stop--go-go-stop-go. Really annoying. Basically all the others I have (MKDS, Pokemon, Diddy Kong Racing [that one is awesome] Pokemon Wii) work great online through this.
Probably the one thing pushing it to the absolute (playable) extreme is Star Wars Battlefront: Renegade Squadron for PSP and being in a room with 15 other people. I try to stay away from things like that but it can fill up fast. Sometimes it's still surprisingly playable, too. I was once 248 on the online leaderboard before my router messed up on me. Then I plummeted.
If you want to see if you can get all that working for you (if you haven't already) go here:
Nick's Wifi With Dial-Up Tutorial
This is the same guy who helped me.
Note again from my own experiences it's best to have at LEATS 36KBPS connection before attempting to play online.
Now, let the flaming begin.

But it's funny how I've played with people before and then told them afterwards and they were like "...whoa. I didn't think that was possible" and then play with me over and over again.
It works pretty good dial-up on dial-up too, as I played Clubhouse Games with someone just last week and had alot of fun and it was fast, too. No lag or disconnections whatsoever.
But again, I have no idea how all of this will work with Brawl. I hope it's like every other game I have except for Strikers.

And Strikers is really fun, too.....
And I'm really good, too. XD
I can't get DSL because I live on a mountain. People who have DSL complain their stupid arguement of how DSL is everywhere now; well, it's not at all. I've met hundreds of people who still have dial-up and can't get DSL.
If I could, I would.
And I also got the Wii Shop to working and although it can take a few tries sometimes to break into it (lol) once I'm there it's fast. Depending on your connection speed, for me, it was 10 Minutes = 20 Blocks.
So download The Lost Levels took approximately 15 minutes.