Stage Swapping

[Jacob8185]

Hi everyone, so I wanted to replace Demonslayerx8, ItalianStallion's Crystal Canyon over the Summit, and use the four versions of it to load randomly using Dantarion's Alternate Stage Loader. However, my version of Crystal Canyon is built over STGMETALGEAR.PAC, and I want to use it over STGICE.pac. How should I make this stage (or any stage in that matter) to go over the STGICE? What files should I replace? I just want to change the STGMETALGEAR.PAC into a STGICE.PAC file, but without the need to use any .rel files. Any suggestions? Thanks!