There is a way but it requires effort so i doubt this is useful to most modders.
Place your SNT objects while playing IV and save 'em to the .ini as per usual. Exit IV and use OpenIV to make a new wpl file with those .ini objects.
What you'll want to do is convert the .ini lines into GTAIV's standard .wpl lines.
1) Place your SNT objects while playing IV and save em to the .ini
2) Use notepad to make a .opl file that has the SNT-spawned objects in it, you'll need to do quite a bit of editing to make the SNT lines turn into opl/wpl lines but it is certainly possible.
Here's a template .opl file with one object spawned, add more lines between "inst" and "end" to add more objects:
| CODE |
# GTA IV Binary Placement File (the # stops the line from being read) version 3 inst x_coord, y_coord, z_coord, rot_x, rot_y, rot_z, rot_w, modelname, 384, -1, 0, -1 end |
Swap out the x_coord, y_coord, z_coord for your objects real xyz coordinates.
The default rotation is "0, 0, 0, 1," so that makes it rotated to it's normal direction. Instead of "rot_x, rot_y, rot_z, rot_w,", you'd write "0, 0, 0, 1,"
Model name is obviously the name of the object/model but if the .ini stores the names as hashes then write something like "hash:500782810" instead of "modelname"
3) Use OpenIV to open the IV pc/data/maps/ folder because that's where the wpl file will go, then drag-and-drop the .opl file into the folder that OpenIV shows. Dragging it like that converts the text-based .opl file into the GTAIV-format wpl file. Close OpenIV when done.
4) Edit your gta.dat to add a line that loads the new .wpl (.wpl is written as .ipl in the gta.dat even though it will load a .wpl file tho, btw)
5) Finished, test in-game.

Example:
| CODE |
x=2473.12 y=615.876 z=-1.42186 h=227.775 Model=1078148491 qx=0.0301864 qy=-0.0681591 qz=0.911797 qw=-0.403818 |
into
| CODE |
# GTA IV Binary Placement File version 3 inst 615.876, -1.42186, 227.775, 0.0301864, -0.0681591, 0.911797, -0.403818, hash:1078148491, 384, -1, 0, -1 end
|
This post has been edited by Frank.s on Monday, Apr 1 2013, 15:03