If there is no dosbox.conf it defaults to autolock=false. I was just using something similar to RGB Classics's code
<applet code="jdos.gui.MainApplet" archive="jdosbox.jar,freddy.jar" width="640" height="480" style="z-index: -100;">
<param name="param2" value="imgmount c jar://freddy.img -size 512,16,2,512">
<param name="param3" value="c:">
<param name="param4" value="autorun">
</applet>
with autorun.bat in the base of the game's image file, giving whatever additional commands needed. This has worked well for me unless I try to use "codebase=", so the jars have to be in the same folder as the page.
Just curious, why are mounting the image as e:? It probably won't matter with the SCI games, but some DOS games don't like not being on C: (with D: for the CD-ROM dive for CD games).
By opening jDOSBox in a frame, do you mean a true frame or an iframe? I'm not sure how possible a true frame would be to do on this site. Would a popup window work, too? An iframe would be a nice touch, but a popup would allow you to navigate away without losing the game, but might encounter problems with popup blockers.