I used a single figure from the Mechwarrior line, mounted on a base, to represent a HWT for my minis. The figure has a shoulder mounted missile launcher of some sort. Pics here:
https://www.boardgamegeek.com/thread...85143#27885143
I haven't figured out the CE yet. Perhaps the single SJG INF figure with a crate on the base or something to represent co-located engineering "stuff" is my current line of thought.
Added edit: I forgot we did use CE in one game we played (one of those "capture the tech" scenarios IIRC). We used a
third color of single INF figure. Thus we knew the green fellow was a CE, as opposed to the blue or red ones who were straight INF