First:
You will need to download TXD Workshop from here:
http://www.thegtaplace.com/downloads/f7 ... rkshop-40b
Second:
Once you have installed TXD Workshop, you will need a mod to install. Once you have a mod (either skin or vehicle)
Third:
Go on the TXD Workshop program and click "Open IMG"
Forth:
Navigate your way to your GTA SA dictionary. Once found go to the "SAMP" folder and click "SAMP.img"
Fifth:
Now click on "Action" and then "Add" then navigate your way to the mod .txd and .dff you have just downloaded.
Sixth:
Once you have opened the .dff and .txd hit "File >> Save" and you have sucsefully installed the mod.
Note:
the SAMP.img will overlap your GTA.img file so you'll need to install SA-MP if you want a fresh non-modded GTA.
Delete:
First:
Open TXD Workshop then navigate your way to GTA SA folder and click "SAMP >> SAMP.img"
Second:
Find the mod you want deleted (.txd and .dff) and delete them.
Third:
Save the file.
Credits to Shadow