How to move trough certain monsters?

[whitevo]

How can i make it so, that:
if player tries to step on monster and the type of the monster is XX then (-- or monster has hidden health)
He can step on the monster
else
it works like it always does, player can't step on monster.

I'm trying to put some light into game trough monsters conditions, because items are not good enough to do it and I don't use OTC yet to make the items with correct lighting.
Problem is that, normal players can't step on these invisible lights. because well.. monster is in the way.

Also, what are these and how can I use them?
registerEnum(FLAG_NOLIMIT)
registerEnum(FLAG_IGNOREBLOCKITEM)
registerEnum(FLAG_IGNOREBLOCKCREATURE)
registerEnum(FLAG_CHILDISOWNER)
registerEnum(FLAG_PATHFINDING)
registerEnum(FLAG_IGNOREFIELDDAMAGE)
registerEnum(FLAG_IGNORENOTMOVEABLE)
registerEnum(FLAG_IGNOREAUTOSTACK)

 

[RazorBlade]

the flags are used for functions like container:addItem and container:addItemEx

container:addItem(itemId[, count/subType = 1[, index = INDEX_WHEREEVER[, flags = 0]]])
container:addItemEx(item[, index = INDEX_WHEREEVER[, flags = 0]])

as for the walking through certain monsters, that'll be a source edit I believe. find where it allows players to walk through each other (non-pvp, protection zones, etc.) and add a modification for monsters.