Vhosts, subdomains and proxypass (probably proxypass )

I have the folowing problem i cant configure my apache to serve like tkat:
if called www.domain.com then apache gets data from domain.com:8100
if called wap.domain.com then apache gets data from domain.com:8200
if called domain.com then apache serves his own documents like a normal
server
all those services must run on port 80 ant i've read the mod_proxy manual
and i couldn't do it.
I know how to:
if called domain.com/www then apache gets data from domain.com:8100
if called domain.com/wap then apache gets data from domain.com:8200
if called domain.com then apache serves his own documents like a normal
server

its a dyndns.org domain with wildcard enabled. can anyone help me?