Okay, then you need to install BeSweet and its GUI. Input to be the *.AC3, output to be *.mpa at 192bps data rate (set in the AC3 page). Tick on Normalize and hit AC3 to MPA button.
Rename the *.mpa file to Encoded_Audio_1.mp2 and copy to your dvd2svcd work folder. Run dvd2svcd, in Misc tab hit the RECOVEr button, browse to you working folder & load in the *.d2s file. Then select Muxing & Cutting and hit CONTINUE button. It will then mux in the audio file and create your SVCD files. Play them in WinDVD or PowerDVD to test them before burning. If all is okay then burn. If not then there is still some problem with the extracted Audio file.