Benignmog: In answer to your original question...yes, of course you can jump start from under the bonnet by connecting to the chassis and starter motor connection...wherever there is accessibility.
Despite good advice above particularly with using a conditioner such as C-TEK, we must bear in mind that no matter how new or cosseted your battery might be, if you are away from home and leave it parked with sidelights accidentally left on, for example, a jump start from another friendly driver may be the only alternative to getting going in a reasonable time.
