Managed to tack on some mods to the pack the server I'm on is using, some that were lost in our move from a custom pack to a modified FTB Unhinged: Universal Electricity, Atomic Science, and Mekanism. I also got PowerCraft to behave with 'em, and Tinker's Construct and GregTech play together without any problems! I feel accomplished. Now, if only the FTB forums would come back up so I can inform my admin...
[ETA]
Got to the admin, and Tinker's Construct has been enabled! I gave him the versions of the mods to download, with instructions on how to (for the client) install PowerCraft, along with a zip containing all the necessary config files. I feel fucking accomplished!