As far as I know of - no - you can't. You can only get back to the Distortion World after you beat the Champion and possibly get the National Dex (not sure if you need the National Dex for it or not) - the portal to get back is in Turnback Cave - the same area where you fought Giratina at in Diamond/Pearl - BUT keep in mind - when you go back there - the rest of the area is cut off. You can only go there to get the Platinum Orb which is the item that changes Giratina's Altered Forme to its Origin Forme.
Jirachi DOES NOT appear in spear pillar, but Dialga, Palkia and Arceus(with azure flute on hand) does.
you have have to catch giritina at the spear pillar on mt coronet
getting 1 at spear pillar is next to impossible if u have really good Pokemon u can trade for it over wi-fi
you can not get the azure flute in pokemon diamond, pearl or platinum unless you use cheats like action replay
spear pillar through mount coronet. look of youtube how to get through. buy minimum 10 max repel to not encounter many Pokemon
go up and find the spear pillar
GO to the spear pillar. go to youtube and write How to go to the Spear Pillar in Pokemon Platinum.
The reverse world is at spear pillar the peak of mt. Cornet
There is no such thing as lunar pillar in Pokemon platinum soz =(
Spear Pillar is at the top of Mt. Coronet (Sky Pillar, where you catch Rayquaza in Pokemon Ruby, Sapphire, and Emerald, does not appear in Platinum).
just go tospear pillar and its only Gratiana's
He is in Spear Pillar.
Spear Pillar
You enter the reverse world by going to spear pillar on top of Mt Coronet, after obtaining the 7th badge, so its not in a town
Spear pillar is located at the top of mt.Cornet.
When you beat the 7th gym leader and have seen everything at the lake you go to spear pillar at the top of MT. Cornet
in the middle of Mt.C