Absolutely. You can use your own VNC client, using the port and ip address specified under the VNC area within your DotBlock control panel. Alternatively, you can use the java-based applet inside of your DotBlock control panel, inside of your web browser (Java Applet required). If you receive an error with Java when loading the applet, follow the instructions here: https://billing.dotblock.com/knowledgebase/191/VNC-plus-Java-issue-Application-Blocked-by-Security-Settings.html
Beyond the built-in VNC capabilities, many operating systems have additional VNC server software which can be installed to allow you to connect with your servers ip and custom created users.