jgreen- it took me a little while to figure out how to make blocks, but it's not really that hard.

If you're using 2010, right click on the top of the palette window, where you switch your palettes around. Select '3D Make' and then pick the draw tab on that one. Draw out the symbol that you want. Select everything, then on the 'Home' tab of the main window, pick 'Create' from the Block section. You'll go through a bunch of options there, and you should be able to just leave everything where it is. Click Okay, and you're back at what looks like your drawing. Set a vertex as the base point for your new block, and then select all the items that are to be part of it - you can do this with a click-drag lasso. Once you've got everything selected, hit Enter.

Now you're in the block editor. Set your stuff up however you want it - I'm still figuring out what some of the things here do - and then click 'Save Block' and 'Close Block Editor.'

At this point you've got a block that's on your drawing, but it's not on your palettes. Select the palette you want it to go to and save your drawing. (It's important that you save at this point, or the next steps won't work.)

Now in your project manager, right click on the project name, and select properties. Expand 'P&ID DWG Settings,' then 'P&ID Class Definitions.' From there, go to the category that you want. If there's a pre-made definition for the item you're adding, then just select it and add your symbol. If there's not, right click on the category name and click 'New.' Anyway, once you've got the definition created, click 'Add Symbol,' and then choose the DWG that contains the block you created, and pick the block. Once you've got the symbol in the little window, then click on 'Add to Tool Palette,' and it'll be on the bottom of whichever palette you've got selected. You can drag it around in the palettes to wherever you want it to wind up.