Can the value and "init" (on startup) be set somehow when creating an nbx object via messages like:

[ obj 50 50 nbx ] ----> s pd-"patch" ?

obj 50 50 nbx 5 14 -1e+37 1e+37 0 (A) empty empty empty 0 -8 0 10
-262144 -1 -1 (B) 256;

in this case, change (A) to 1, to set init to ON, then change (B) to the value for startup.

to find out how to do this for sliders or other objects, just make a blank patch, and then add your slider or whatever, and save that patch. If you open that patch as a text file, you can see the various settings. I'm not sure if there is any documentation on what each value does, but you can just figure it out with trial and error.