No, changing speed requires re-encoding and eac3to can only encode to the following formats:
(1) RAW, (L)PCM
(2) WAV (PCM only), W64, RF64, AGM
(3) WAVs (multiple mono WAV files, PCM only)
(4) AC3
(5) DTS
(6) AAC
(7) FLAC
You can output to WAV and encode that to eac3. But be aware there are different eac3 "flavors":
https://forum.doom9.org/showthread.php?t=174418