Forester

Hi, I am using MCPC+ builds with the newest Forge inbuilt. I have a more general question about Forge in combination with Forge mods. I would like to know how to use the /give server command on blocks / items that use 'combined' IDs (which is from what I understood how mod programmers try to save ID space). I know how to /give items from vanilla MC (since there is an ID list) but not yet how to do so with mod items / blocks. Cheers, F.