|If you have enough skill points to hide and stealth, you can perform a shadowjump while on horseback.
First, get on your mount. This works for both ethy's or real mounts. I didn't test nightmares or other taming related mounts.
Next, use the hiding skill to hide. Wait for the skill delay pass, then use the STEALTH SKILL to stealth. Do NOT walk or move to auto-engage stealth mode, you MUST use the stealth skill buttonicon to "begin to move quietly."
Once you "begin to move quietly" then you can shadowjump. Easy as pie. This is a great way to move around in places where being revealed on foot would mean death.