suanLoBeach I'm afraid this question is a bit vague, so I'm not sure if this is the answer you're looking for. However, if you want to create texture packs for multiple Spine projects, you can do so using a script. The following export scripts may help:
Blog: New export shell scripts
That said, while I mentioned "at once," the packing itself is still done on a per-project basis. The script simply searches for the target Spine projects and packs each one it finds. In that sense, you cannot truly pack multiple projects simultaneously.
Nonetheless, the script is quite useful, and we recommend it to all users. If you haven't tried it yet, I highly encourage you to give it a go.