If he means ciso files, then yes the WiiBackupManager can output such files.
But USBLoaderGX nevers asks the user to convert a game to a "ciso" format.
just in case he still want to use this format, USBLoaderGX is working fine with all three format: .ciso .iso and .wbfs
ciso is a compressed ISO file format, it's like a WBFS (in the way it keeps only the useful data and remove dummy fillers), but without the WBFS partition headers.
I guess you are still looking for an answer to use your games with USBloaderGX:
You have two solution :
1- Dump/install your game on HDD using the USBLoaderGX internal Disc copy function. (insert a disc, select Install) That's all.
2- If you have the ISO on your computer, you can convert/move/rename the game automatically using WiiBackupManager:
Preference > FAT32/NTFS tab > Filename convention : select "Filename_[GameID]", and close the preferences.
File tab : select your ISO file
HDD1 tab : mount your Drive letter
File tab : check the game you want to put on your HDD and select the menu "Transfer > Selected > to HDD1".