Not sure how to help with how to do it with a COM Component, but I did write up some instructions for how do compress a PDF from the GUI in PDFCreator. It has worked for me and others.
Below is that info... not sure if it will translate from my copy and paste correctly or not..... maybe it will help you....
Compressing/Shrinking a PDF Document with PDFCreator
Sometimes PDF Document can be very large and hard to email or share. This is especially true with PDFs that were created from a scanning or have many pictures embedded in them. Compressing a PDF is useful however the graphic quality in the PDF may not be needed for some levels of printing or sharing. So it is advisable to always keep a copy of the original file.
To shrink a PDF using the free PDFCreator tool do the following:
Print the PDF document to the PDFCreator printer that you have installed.
After the document printing processing is complete a new window will pop up that say PDFCreator and the version number. It will have information on the Document Title, Creation Date, etc. At the bottom is a button labeled "Options". Select the "Options" button.
In the Options window on the left side open the "Formats" group. Then select "PDF" in the "Formats" group.
The first tab "General" has some over all PDF format options. Note however shrinking the resolution on this page has generally not shrunk the size of the PDF.
The next tab "Compression" has several items to configure.
Make sure "Compress Text Objects" is selected.
Under both sections Color Images and Greyscale Images make sure Compress is selected and the drop down compression type from "Automatic" to "JPG-Maximum".
After the previous change "Resample" will no longer be grayed out. Select the check box for "Resample".
Make sure the box below "Resample" says "Downsample" then change the "Resolution" from 300 to to 150. Note one can change the resolution to a lower "Resolution" like 96 but the quality will continue to degrade. A resolution of 150 is often a good middle ground.
For the next section "Monochrome Images" make sure "Compress" is checked and that CCITT Fax Compression is selected and Resample and Downsample as above are selected. Extensive testing of this resolution has not occurred but changing the Resolution from 1200 to 600 would be advisable for shrinking file size.
Select any other configuration options that are desired.
Select Save for the "Options" Window and then save for the original PDFCreator window. Select your file name and location and safe the file. For the compressed version of the file one might use the same file name as the original, but add the " - Compressed" to the end of the file name so you know it is the compressed version.
View the PDF and check the file size to make sure the are acceptable.
After you have compressed the file(s) as desired it is best to go back and reset the setting to the default unless you want them to be kept for future documents. Go back to the above mentioned "Options" section and click on the button at the bottom of the window that says "Reset all settings".
The WPS Compress PDF Online supports 3 compression ratios (HD, Recommended, Smallest). You can choose one ratio based on your requirements to compress your file while maintaining high quality.