I want to recompile the Amiga version of Bitlbee to include proxy
support. All nececarry sources are already in the Bitlbee
archive available here, only a recompile is needed (see
Bitlbee Proxy_Howto):

But I really don't know how to compile this stuff. I have the MorphOS
SDK installed, but the Bitlbee source needs "glib.h", which I don't
know where to search for.

Any hints from the dev gurus here? :)

Bitlbee has it's own Site.

Better get current sources ... on my site is only a link
to the amiga client on aminet

The amiga client comes with the amiga sources and to my knowledge they are modified, so before trying the latest sources it would be easier to recompile the amiga sources that come with the client I think ;)