VideoPaint from Ulead allows this, you can also find a tool to export to a filmstrip and do this in photoshop, you can export individual frames from Vegas with any number of both free and purchased scripts, import to Photoshop or other graphic tool, then reimport as sequential frames to Vegas.
I would really look at fxhome unless you will be using photoshop alot after this project. For 90 bucks you get a decent compisitor with keyframeable animation. and all of your choices you would need for lasers are already there(color,glow speed etc)
Also just to let you know where i am coming from, We mentor high school programs, and a very common high school production involves Light sabers and lasers. We have tried all avenues Photoshop,Vegas,combustion(my favorite), and fxhome beats them all in speed, and ease of use, let alone price.
Thanks for all the help, however, after viewing the FX software and trying ut the demo, I noticed I was only capable of doing the light sabers and explosions. Is that all the program can do? I was looking for something like paint.