Hi Milind,
currently the only way would be to pass the parameter on URL when launching Design Studio application from launchpad. you can use the global script variable with "URL" flag.
optionally, you could create your ouwn SDK component which would hard-code the URL in ZTL script - and then the application would use this SDK component. This has the value, that change in this SDK would immediately affect all applications with new URL (if you wish, can give you here some code snippet).
Unfortunately, there is no other option for now to dynamically read and access in BIAL any external parameters via RFC or similar web service.
Karol