Nothing special required in AC3D to do it... just planar map your object and use the same exporter as usual. You'll need an LSL script to switch the sculpt mode.
Like so:
Code:
default
{
state_entry()
{
llSetPrimitiveParams([PRIM_TYPE, PRIM_TYPE_SCULPT,"your-texture-name-or-uuid", PRIM_SCULPT_TYPE_PLANE]);
}
}
Here's a tablecloth I did that way: (Just a plain old divided plane with a scalloped edge, draped.)