OpenBSD has
umsm(4) and
ubsa(4), they are used by several cellular modems.. most of which have quirks where they appear as CD-ROM devices (..with a Windows driver).
From the output you've show, it appears to be detecting the MMC slot on the device.. so you can read from memory cards.
Perhaps this device has a "mode select" functionality that will allow you to switch it into behaving like modem?
The OpenBSD project isn't likely to accept GPL licenced code, so porting anything over from Linux wouldn't be the best decision.
Here is a mailing list thread about your specific modem, maybe it's enough information to get it working.
http://marc.info/?t=125530931300002&r=1&w=2