It uses the BASS library, right? If I remember correctly this library uses DirectX, so someone should port this library. I don't know about HawkNL.. Next to that, I'd love to see a port as well. Especially because I can't play it on my mac..
Some kind of version of Liero would rock. The online Liero community was the first I ever got involved in. Had a grand old time there for a good while, but left about four years ago.
Liero itself wasn't open source, but there were a lot clones being worked on by other people. One of the forum members even backwards engineered the original to make a windows native clone. If you ask me, this is the one that should be ported, because he set out to make a Liero "port" that was more or less the same exact game.
Why don't you port gusanos (gusanos.sf.net)? It's the best open-source liero clone atm (LieroX is kinda sucky and Gliptic stopped coding for LOSP, as he joined the gusanos development team).
I (as a atm quite active member of the liero community) would be very happy, if someone did a port.