Sorry Barbara but I can't find the notes I made in 2009 when this first came up so at the moment I'm working off the top of my head.
Our version of usb-modeswitch was ported from the Linux version here
http://www.draisberghof.de/usb_modeswitch/ On that site there is a little more information that might be of use to you.
Now another question. What do you get when you type ppp in an OS/2 window after your usb modem is mounted?
The ppp usage is as follows if you need to know.
┌─────────────┐
│ PPP │ OS/2 TCP/IP Point-to-Point Protocol Driver
│ 2.00 │ Copyright(c) IBM Corp. 1994, 1995
└─────────────┘ Revision: 1.18a 10 Jan 1997 00:00:00
Usage: ppp [options], where options are:
<device> Communicate over the named device
<speed> Set the baud rate to <speed>
<ip>:<ipdest> Set the local and/or remote interface IP
addresses. Either one may be omitted.
asyncmap <n> Set the desired async map to hex <n>
auth Require authentication from peer
connect "cmd" Invoke command cmd to set up the serial line
Ex. connect "slattach atdt9,999-9999 CONNECT"
defaultroute Add default route through interface
file <f> Take options from file <f>
idle <n> Set the idle timeout period to <n> minutes.
modem Set/Reset modem control lines
mru <n> Set MRU value to <n> for negotiation
netmask <n> Set interface netmask to <n>
notify Display notification message when DCD signal drops
priority <n> Set process scheduling priority to <n>
rtscts Use hardware RTS/CTS flow control
silent Don't send connect request to peer, wait for request
If you get some indication that ppp sees the modem on the com port it shouldn't take too much to get you connected.