http://www.example.com/somewhere/your-miner.zip arg1 arg2 ... argX

Preparing custom miner package:

Create folder with any name, for example "myminer-v1.0.0".
Put miner files directly into this folder.
Change main miner executable file to "miner" (with lowercase letters and without any extension).
Pack whole folder into ZIP format and name archive file with name of your miner and its version, for example myminer-v1.0.0.zip. The name of archive file is very important because if Your rig download once your miner package and than You will prepare updated package using the same archive file name, the Rig will be still using actually downloaded package with the same filename from the local Rig cache.
Upload the archive file with the world wide readable website available for download via http, https or ftp protocol.
If Your miner will not work, and requires from You some fixes, You schould prepare new package with fixes using different archive filename, for example: myminer-v1.0.0-fix1.zip.
Properly prepared archive schould have structure like below:
myminer-v1.0.0.zip (archive file)
    |- myminer-v1.0.0 (folder)
        |- miner (main executable miner file)
        |- kernels (optional subfolder with required files by some miners)
        |    |- file1
        |    |- fil2
        |- config_file (config file and other required by miner)
        |- libcudart-10.0.so (others required libraries, that are not included in SimpleminnigOS)
 

Using custom miner:

Complete the "Miner OPTIONS" field like in below examples:
http://www.example.com/somewhere/myminer-v1.0.0.zip -algo MyCoin -server pool.example.com -p x [...]
ftp://ftpuser:ftppassword@example.com/somewhere/myminer-v1.0.0.zip -algo MyCoin -server pool.example.com -p x [...]
First argument must be the URL (without spaces and special characters) of miner location
Others argument are passed to the miner same as in case of using regular miners