Welcome to CPF cybertek03. As you can see by the number of posts, I'm a little new myself. Someone who knows for sure may chime in, but I beleive the stock E1B clip will fit the L4 body, no modifications. You could search the forums for another detailed procedure on changing the clip, but here is my version to follow at your own risk:
1. Remove the head.
2. Remover the o-ring carefully (use something like a toothpic to seperate it from the body - nothing sharp).
3. Note the placement of the plastic shim under where the clip attaches to the body so you can replace it correctly.
4. Place a string or lanyard under the clip so that you are able to pull the clip off the front of the body. Pull clip off in an area where the shim cannot fly too far so that you won't lose it when the clip releases suddenly.
5. Place the shim and desired clip toghether and slide into place. This can be somewhat difficult so make sure the shim and clip are properly alingned with the slot and remain straight until slid completely into place.
6. Replace the o-ring. Ensure that the clip is not interfering with the o-ring.
7. Replace the head.
I don't like to remove and install these clips more than necessary, so I wouldn't even try the clip from your E1B. I'd just wait until you can come by another E1B clip.
hope this helps,
bezel