If any program can handle conversion of .epp files (images) to .el2 files (stickers), it would be Easy-PhotoPrint EX from which both of these file type originate. You can get it from Canon website, or from a CD bundled together with your printer.
Convert Easy-PhotoPrint image files to Easy-PhotoPrint EX stickers file.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert epp to el2 on Windows
A program for creating albums, calendars or stickers from digital photos
Convert from epp file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.