You cannot have two paragraph styles in one paragraph, but you could use different styles in each cell of your table and include them all in the TOC.
As far as using a different paragraph style for the lisitng in the TOC and the actual text that is picked up, that's very common. It allows you to find many different paragraph styles to include, but have the listings all look the same, and completley different from how the text looks in the body of the book. You'd problay not want 24 pt Bold TOC lisitngs, but that might be appropraite for section headings that you want to pick up.
My actual concern is regarding Ligatures.
How to merg various paragraph tags (table headings) as a single entry in the TOC.
Example shown in above thread: IP31/42 T40
So you want to automaically concatenate different cells into a single paragraph in the TOC?
I don't know a way to do it that you're likely to find acceptable for more than one or two entries (since they involve adding non-printing substitute text to your pages to be picked up for the TOC). It might be possible to devise a Find/Change query and script that could do it to the generated TOC, if there's a pattern that can be applied to all enties, though.