I'm certainly hoping you aren't asking how to move the origin... because you definitely can't do that. If you're not... I think what you're asking is how to make a brush an origin brush? If so, I'm pretty sure it's just a texture. Cover a brush on all sides with the origin texture or it won't work right.
Are you trying to make a rotating door or something?
Well... that IS where you get an origin brush. Any brush covered with the origin texture IS an origin brush. There's no other way to get an origin brush.
It's totally different in source, though. That is to say, there are no origin brushes in source.
btw to make a origin u can use aaatrigger texture 2 u know
1. Find zhlt.wad in your ZHLT folder.
2. Load zhlt.wad in Hammer.
3. Look for the ORIGIN texture in zhlt.wad.
4. Apply the ORIGIN texture to a brush, and it will become an ORIGIN brush.
**Don't use aaatrigger instead. You can, but don't.