It is possible. All you need is an icon and an entry in menuconf.tab.
But since menuconf.tab is... let's say a little tricky, it's also tricky to explain.
You'd need a line in the road tools (waytype 1) section, something like this:
red numbers need to fit into your road tools section (if the last entry says e.g.  make yours  and put it beneath it - if you do this wrong, many things in menus may not work properly anymore until you fix the error, so I strongly advise working carefully here!), blue is the icon number (a separate file, with its name here, might also work - but I never tested that).
Again, for most inexperienced users, I would not recommend fiddling with menuconf.tab. If you insist on trying, please make a backup of the orginal file first.