Cultivation
Difficult to extremely difficult. There's only been one successful cultivation attempt that I know of.
This was done by Aaron a few years ago.
Two glass slide samples of spores of Psilocybe weilii were provided for cultivation experiments. One slide was labeled as produced from a mushroom growing in August (Strain.2#.)and the other was designated as September (Strain.D#). A sample from each slide was placed a petri plate of standard malt extract media agar with gentamycin sulfate antibiotic. All plates showed visible germination in 6 days at 78F with no signs of competing organisms. At 14 days the most vigorous mycelium was selected and transferred to individual petri plates, with a standard potato dextrose yeast agar, in 7 days all had grown out.
Fruiting substrate
Hardwood sawdust 12 cups, cow dung 12 cups, wheat Grain 8 cups, verm. 4 cups, water 12 cups.
Place the substrate into a pillowcase and put it in a 5 gal. bucket, add enough water to cover medium and soak for 12 hours, then drain and put it in the jars and let the jars set for 12 hours then sterilize for 1 hour at 15 p.s.i.
casing layer
Peat moss 7 cups, verm. 3 cups, perlite 2 cups, water 6 cups.
The casing was sterilized for 1 hour and left to sit for 7 days before it was applied.
Procedure
Day 1. Agar transferred to fruiting substrate 7#.
Day 7. Jars were shaken.
Day 14. Fully colonized.
Day 14. Cased and put in the light.
Day . Bad overlay.
Day 35. Overlay was scratched off.
Day 50. Pinning (1 out of 15) (Strain.2#).
Day 56. Growth Stopped. (Strain.2#).
Day 57. Pinning (2 out of 15) (Strain.D#).
Day 71. (Strain.2#) Has made 2 more pinheads.
Day 71. (Strain.D#) Has made 8 pinheads.
Day 72. (Strain.D#) Has made 10 pinheads.
Day 76. (Strain.D#) Has made 12 pinheads.
Day 81. Growth Stopped. (Strain.2#).
Day 81. (Strain.D#) Fruitbody are 2 to 2.5 in. tall.
Day 82. Veil's broke.
Day 88. Fruitbody were harvested, 3.5 to 4 in tall.
Notes
1. No overlay occurred on (Strain.D#).
2. The one strain from the August print (Strain.2#.)did make pins on day 50 and day 71 both aborted.
3. Diffuse sunlight and 13 hours/day of fluorescent light.
4. Temp. 68. to 75.F.
Strain.D produced four flushes of robust fruitbody and the experiments was ended at that time. Psilocybe weilii seems to be resistant to contamination when compared to other Psilocybe species.
Photo/text credit - Aaron 
This photo below from Workman shows P. weilii fruiting on agar.
Cap: 2-6 cm broad. Campanulate to bluntly conic with an inrolled margin when young, then incurved, often with an irregular, soon expanding to broadly convex to nearly plane, to uplifted in age. Dark chestnut brown to deep olivaceous brown, typically with a blackish brown zone around the disc, where flesh is 3-4 mm thick at its center. Strongly hygrophanous, fading in drying to pallid brown to light brown. Flesh whitish, bruising bluish. Surface viscid when moist from a separable gelatinous pellicle, translucent-striate near the margin, which can split in age and become tough and opaque in drying.
Stem: 25-70 mm long by 4-8 mm thick. Equal, swelling towards the base, which projects white rhizomorphs. White, becoming dingy brown, bruising bluish overall in age or from drying, covered with a well developed sheath of whitish fibrillose patches below, and pruinose above. Cartilaginous, strigose, hollow, stuffed with a whitish pith. Partial veil cortinate, leaving a fibrillose annular zone sometimes dusted with purplish violet-brown spores.
Gills: Attachment adnate to sinuate with two tiers of intermediate gills, close, even, broad, light brown overall with pallid, floccose edges. Becoming dark chocolate brown at maturity.
Microscopic features: Spores dark violet grayish black in deposit, subellipsoid in side view, subrhomboid to subellipsoid in face view, 5.5-6.5 by 4-5 microns in side view. Basidia 4-spored. Plaurocystidia abundant, subfusoid or ventricose-rostrate with short apex, or sublageniform, 10.5-24 by 5-10.5 microns. Cheilocystidia lageniform with short, single, or branched neck, 20-37.5 by 5-6.5 microns.