I tried to apply a Teleporter Frame for Mekanism to a Carpenter's Slope - the game just placed it next to the slope. Turns out that the blocks simply will not work with anything that does not have a 16x16 texture (by default). The block that I have mentioned has a 32x32 texture.

--EDIT--

I just wanted to link this with FMP support - whichever block FMP supports, it should support (like with the lapis caelestis blocks from ExtraUtils - CB does not support those, as it automatically chooses blocks to support). Blocks that this supports can also be added to the list of blocks the FMP supports, when both mods are present. Should I go the the FMP repo and ask about it there?

(Or should there be a separate config for which blocks that aren't initially supported can be given forced compatibility?)

Texture size is transparent in game code. Block support isn't determined by texture size, but by whether the block returns "true" for whether it renders as a normal cube. There may be other ways to determine if a block can be a cover.. but this is the best way I've discovered so far.

FMP has a config that allows forced block support. I was thinking of merging the two systems so that support for blocks on both sides would work for everything.