This is my first comment in this community, and I am happy to inform you that this is possible, or at least I did the bridge setup of my TC 2Gb 2011 model with a FritzBox 7390 Modem/router.
And it works great. Yesterday I did some downloads in my Parallels Win 8 VM using uTorrent and it reached almost 2Mb in download, using ADSL line in Italy.
As for the step by step guide, I don't recall it well but I am pretty sure that you will be prompted to select if you want a bridged connection with your existing router.
From your other post in TC area.
You are not wifi repeating.. you are roaming.
You have an ethernet connection between the Fritzbox and the TC..
That is always going to work fine.. that is not wireless repeating. You are creating a wireless signal on the TC completely separate from the Frtiz.
Wireless Extend or repeater means there is no wires at all.. it is extending wireless using the original wireless signal.. It will not work because Apple use proprietry system.. !!