The only sources of Excalibur in standard Nethack are as follows:
- Arti-wishing for it (not guaranteed if 2+ artifacts exist in-game)
- Dipping as a lawful character
- Being Crowned as a lawful character while wielding a non-artifact Longsword
- Finding it from the bones file of a character with it
Ignoring the final option because it's RNG and gamey, the short answer is no. It's also worth nothing that even if you do arti-wish up an Excalibur, it is an intelligent artifact and will blast your unworthy, Totally Not Lawful behind when you wish for it and when you wield it. (4d10 damage, or 2d10 with Magic Resistance. You do have Magic Resistance, right?)