To see the new skin almost instantly, use the sequence below to deploy online:
# Invoke wlst (weblogic scripting language)
./wlst.sh
# Connect to WLST
connect('<WEBLOGIC_ADMIN>','<PASSWORD>','t3://<IP_address>:<PORT>',adminServerName='AdminServer')
# Change directories to the list of servers.
cd ('Servers')
# Deploy new skins and styles
deploy('<APP_NAME>','/<LOCATION>/custom_skin_style','<BI_SERVER>')
The skin / styles only needs re-deployment if you change the directory structure. Its not needed if you're adding new files only.
Hope this helps,
DR. OBI
P.S. WebLogic and WLST are important for nimble application deployments, it helps to use it where you can. John Minkjan has some informative blog posts on this area.