1) Maybe you can find a custom modpack for the server in the tachnicpack site:
http://www.technicpack.net/modpack/list
2) Alternatively to download:
http://mirror.technicpack.net/Technic/servers/voltz/Voltz_Server_v1.1.3.zip
Open it up with Winrar/7-Zip and such, get the mods in mod folder, and insert them into your:
C:\Users\USENAME\AppData\Roaming\.techniclauncher\voltz\mods\
Where USERNAME is the name you have set in your computer.
This will manually update your mods- But do not change anything in Techniclauncher options or the old ones will be downloaded again.