As far as I am aware Attract Mode is unable to do this.
Here is an example of two loadiine format rom's file structure:
/Mario Kart 8/code/Turbo.rpx
/Super Mario Maker/code/Block.rpx
As you can see the roms are in a separate subdirectories. They are not named after the game, so the filelist would look weird. They cannot be moved or renamed or the emulator will not read them. There are no tools to convert loadiine to another file format.
Is there any way around this?
Edit: Apparently you can rename the rpx file, so I gave them all the same name. Oh well.
If anyone in the future is reading this, I did:
args -g "[romfilename]"\code\go.rpx
romext <DIR>
Although I wish I didn't have to do this hacky thing every time I get a new game.