The SE515 hardware is the same as the Dynalink RTA770W. In fact it is sometimes referred to be RTA770BW where B stands for Annex B but the ADSL modem can handle both Annex A and B. This just depends on the flashed firmware.
There is no running OpenWrt up to now!
But now the complete sources can be downloaded at the Siemens Homepage:
From the README:
This release contains all of the files needed to build a SE515 DSL Router image. To build an image, enter: # make PROFILE=
Here can be found some hints how to compile and use it (in german language)
Below the reset button/on the left of the switch processor (BCM5325…)
serial connector J304
|---| front | o | 3.3V of | o GND the | o Tx board | o | Rx |---|
Console is active after login.
In the bottom left corner. Soldered on the picture. Typical 12 pin header
Pin one is in the very bottom down part of the header. Jtag is fully operational.
Note. Don't be afraid of the German language - just use babelfish or any similar service.