Probably. Not enough information to give a comprehensive specific answer.
Routes are added and removed as interfaces (physical or logical) are activated and deactivated. The interface activate action adds routes, and more recently added routes are (generally) used in preference. What probably happens when you login to the VPN is a new logical network interface is created/activated, and the routing table is updated to use it by default. Assuming the Juniper client creates a tunnel interface, and does not also add a local host-firewall (and that you are not violating corporate policy -- it's possible that this is intentional), you should be able to
replace the default route (setting it back to your home router via ethernet/wifi interface),
add specific routes to the corporate network via the tunnel interface.
The MSKB 140859 in the question you link to provides much of the theory, but not so much of the practise.
If you understand the theory, running netsh interface show interface and route printbefore and after connecting should be useful.