Is it possible to have a technic modpack locally?

It is possible in technic launcher (build 204) by editing %appdata%\.technic\installedPacks.

1. Use Launcher to download vanilla or another pack you want to use as base for modepack
2. Close launcher
3. copy "source mode pack" to new directory in %appdata%\.technic\modpacks
4. in installedPacks create new block for your new pack:

"My pack": {
"name": "My pack",
"build": "recommended",
"directory": "%MODPACKS%\Mypack"
},

5. in same file add new row in "byIndex" list

"byIndex": [
"official-crafting-dead-mod",
"carovny-minecraft-magic-mc",
"vanilla",
"My pack"
],

6. Start Launcher and your pack will be listed in modpack section.

hey i understand your want for a custom modpack, there is a very simple easy way to get a custom modpack with just a few clicks (can have 200+ mods). one catch it isn't on the technic launcher, you have to use a launcher called "AT Launcher".

1. download the launcher (The AT Launcher)
2. open the launcher and go to the packs page
3. scroll down until you find "Solitary Craft"
4. click the New instance button next to the pack
5. select the mods you would like in your pack via the pop-up window that appears within the launcher
6. wait for mods to download
7. play and enjoy

I recommend using a different launcher like MultiMC. The old Tekkit Launcher supported custom zips, but the new one handles everything automatically through the Technic Platform.

What i did is for example i wanted a ships mod from a modpack(pirates at sea) and i wanted it in hexxit. all i did to have hexxit and the ships mod together was go into the pirates at sea folder go to modpacks copie the ships mod paste it into hexxits mods then copie the config file for the ships mod and put it in hexxits config folder.

the modpacks also im pretty sure have to be for the same version of minecraft.