The Eremurus should be planted in a shallow hole, onto a little pile of horticultural grit, to aid drainage. They should be in full sun and not crowded by other plants (very important if they are to survive). Spread the 'starfish' roots out and cover with soil. Leave the large bud just below the soil surface.
The Eucomis needs to have the top of the bulb just poking above soil level, like you would plant an Amaryllis. And also in full sun.

I have my eucomis at least 4 inches deep and it has so far survived 4 yrs. I hope it has survived this winter.

Mine was in a pot, so 4 inches deep would be out of the bottom!! I let it die last winter as it was terribly smelly when the flowers opened! I thought the drains were blocked!! We had to banish it to the bottom of the garden it smelt so awful!