Hi , What is the reason you need to do this way .. just want to know if the below solution helps you or adds complexity ..
you have an option create a virtual service from raw_traffic file and also you can build VS using command line utilities where u don't have to login to devtest ws..
for this you need to do some sort of pre-work..
1. prepare raw_traffic.. there is particular format which lisa can understand and build virtual service so you need to make sure your req and res follow that format.. i know manually it is though to build raw_traffic the way lisa wants but you can have some automated scripts (ruby, groovy) which can extract your request and build raw_traffic..
2. write small command line script .cmd or .sh ,,, where it will accept raw_traffic and build VS and deploy VS to wherever you want..
I know the above option is not so easy but this is the way have been done for one of the use case where req and res will be shared on the wire as part of continuos deployment and testing..
you can explore rest api for detest if anything for this.. i have not used those much apart from stop , start use etc.,