this method is probably not going to work for many mods, however if this method is confusing for you i have done it with some mods by simply changing the info.json file inside the mod to change the reference from 0.17.xx to 0.18.0 this usually requires the mod to be extracted first.
for windows, use at your own risk.
1. open the mod folder '%appdata%/factorio/mods'
2. open the mod by double clicking (if the mod is already extracted skip to step 7)
3. copy the folder inside the zip
4. up one level (up arrow beside the folder name at top, return to the mods folder)
5. paste the folder from the zip in the mods folder.
6. delete the mod zip or move it to another folder that is not inside the mods folder.
7. open the extracted folder by double clicking.
8. open the 'info.json' file in notepad or notepad++
9. edit the line that shows - "factorio_version": "0.17", - and change 0.17 to 0.18
10. save the file and try to launch factorio.
if it fails to load then you will need to wait for an update from the author, i recommend deleting the extracted folder and attempting to obtain the mod from the portal after it has been updated.
edited for correction