Is there a mod, or better off, a code out there that allows this to happen?

Code? No. Mod? Yes. AwesomeMod and Master Controller both have options to disable the clothing filter, or in other words, make your Sim be able to wear anything in any category, including the nude outfit, singed outfit, and the Simbot and Mummy bodies. With AwesomeMod, open the cheat box with ctrl+shift+c and type in "disableClothingFilter true". With Master Controller, click on a computer, then NRaas/Master Controller, then Settings/Disable Clothing Filter.

Alternatively, if you don't want to go totally whole hog on this, you can just convert over the items you want using Delphy's CTU (or probably TSRW, though I can't tell you about the latter). For information on that, go over to the CAS Parts forum under Create.

If you're looking for a premade mod, though, the place you want to head is to the "Where Can I Find" forum under the Help menu.

I created a lesson on converting categories in TSR Workshop and another using S3pe.

The problem is that i have installed a bunch of CAS-slider mods that will conflict with AwesomeMod, so i can't use that.

Master Controller shouldn't conflict with those.

Sliders that conflict with AwesomeMod? I have the leg, arm, and body height sliders, body girth, the breast sliders (which I've been meaning to take out), Jonha's butt, hip, waist, shoulder, thigh, calf, and chest sliders (including the base), and the male and female belly sliders, and AwesomeMod doesn't conflict with them. Besides the eye stretch, width, and the rest that come with those, what else is there?

Sliders cannot conflict with AwesomeMod, because AwesomeMod doesn't have anything to do with sliders.

The sliders do conflict with awesomemod only if the sliders you have are core mods.

There is no such thing as a slider that is a core mod. If it were a core mod, it wouldn't be a slider anymore.