Hi 0Forest0,
You can create a network published shared variable that refers to a custom control. When you're creating the variable, you scroll to the bottom and choose From Custom Control... as shown in the screenshot. This will prompt you for a .ctl file, where your control should be saved. Then you can use this variable with a custom datatype.
Also, in order for your program to run at startup, you need to build the program by right clicking the build specification and selecting Build. You won't get an interactive front panel in this situation, because it's running as a real-time executable on the target. All you will get is any data you're sending back to a host VI.
C. Weeks
Product Support Engineer
NI