A couple of simple steps to get you going:

1. do make (suitable Makefile is in the source dir)
2. copy over andy's vifinit script to local dir
3. copy over xenolinux guestos image (NB. image needs to be uncompressed, so
if the only image you have is image.gz do gunzip image.gz before doing 
anything further)
4. add executable permissions to newdom and vifint
5. edit newdom script and change it as it suits you

newdom script takes guestos image file name as first parameter and newdom id
as second parameter, eg.:

./newdom xenolinux 1

should initiate building of dom1 with the image contained in file named 
xenolinux in local dir.

in general, domain_builder application takes three parameters: requested 
memory in kb, guestos image file name and number of vifs to be created, eg.

./domain_builder 16000 xenolinux 1

would build domX reserving 16MB mem, creating 1 vif and using os image stored
as xenolinux in local dir.

happy booting!

boris