[pptp-server] VPN via modem connection

[BC]

hi folks

does anybody know a way to connect a win98 client
to a PoPToP server in the following way:
the client should connect via modem to the internet and then a 
tunneled encrypted connection to a linux server should be 
established.

the difficulty is that if win98 already uses the modem adapter it's 
not able to use the vpn adapter... (why? these should be different 
devices)

any suggestions? thanks in advance!

bart