As regards drainage, are you sure it doesn't drain well in the first place? I say this since not amending the planting hole at all, but only working the spot (large, not deep), is often best, since 'uniform' soil around the rootball helps with uniform distribution of water.
No vermiculite: it breaks down fast and becomes a problem. Not sure about advisability of sand, either (certainly no sand in containers - does it help in situ?)
Make sure you work on the rootball, and get rid of as much of old soil as possible.
About the manure: I haven't used it. May be he means too much could burn roots - but someone else might want to jump in.
Good luck.

I personally think you should be fine ...it's not in a container which from what others have written here would be a problem ...to be safe I would do as schusch says and dig really large holes wide and deep (Don't plant deep !!! back fill only !!!) and put a a NON - fertilized soil mix that drains well in the hole...what that does is keep any of the fertilized soil out for at least a year when it will definitly do no harm ...although i personally don't think it will anyway left as is ...but better safe than sorry.( rain may drag some of the nitro in but probably not much!! ) As Je Miller says dig a thousand $$ hole for a ten $$ plant or something like that a good adage for any tree IMHO. Jm's are pretty hard to kill unless they are pre infected with disease or you plant them in a swamp!!! so I don't think you should worry too much .. David

Schusch and myersphcf -- thanks for the great advice! I think the point is well-taken about making the hole really count! I'd say my soil gets a drainage grade of about a 'B,' rather than and 'A,' but it's probably worth checking it a little more systematically with a proper drainage test. I think the seller did mean that the roots could burn -- he said the delicate variegated leaves would turn brown with too much fertilizer.

One follow-up: Any suggestions for "NON - fertilized soil mix"?

How about from another spot in your garden, where you didn't add manure? Or from a neighbor? You don't need that much: in any case do mix with surrounding soil at least, since all different soil will behave differently water wise, and it will be more difficult to have a uniform moisture supply (which is also why you should try to get rid of as much of the old container soil as possible).

I believe it is not so much the manure but does the soil have the proper bacterial complex to deal with undesirable bacteria and the same goes with soil fungus. With out good bacteria bad bacteria has a field day. I inoculate every thing including all of my trees with friendly funguses and bacteria. As to potting mixes I boil it and then inoculate it as well with good bacteria. With out good soil bacteria your trees can never build any resistance to bad bacteria and funguses.
That said this this is one site I prepared for a ten dollar tree: a href="http://photobucket.com"; target="_blank">{{gwi:1040892}}