Can I use the pfctl command in Terminal to throttle bandwidth?

The ISP I use (Northwestel) limits my upstream bandwith to 2 Mbps. While I upload at that maximum rate, the download service is disabled.

Plus, if I upload at that maximum rate for any sustained period of time (sustained being longer than about 5 minutes), my entire service is disabled and requires that I reset the modem to start it again.

As you can imagine, this is very frustrating. Especially when you consider I pay $125 a month for the service.

Very few apps offer an option to manually throttle upload speeds. Dropbox, for example, does. But Apple's PhotoStream does not.

So I'm looking for a way to globally throttle upload speeds on my Mac to a rate less than 2 Mbps so that I can avoid the above-described problems.

This has led me to the pfctl command in Terminal, which – from what I've read – would allow me to set an upload rate maximum limit in the Mac OS Mavericks firewall. The problem is, I'm a novice command line user and so can't figure out how to compose a command properly.

Does anyone know how to compose a pfctl command that would enable me to limit the upstream bandwidth rate on my Mac to about 1 Mbps?

Alternatively, is anyone aware of another way to globally set an upstream bandwidth rate limit on a Mac, perhaps a utility or app?

Any input or thoughts will be gratefully accepted.