of course
I've done it a couple of time in both ways.
Use PSXGameEdit (http://www.moberg-dybdal.dk/psxge/) to extract the single save file you want to transfer from ePSXe's memcard file (you have to rename to the correct extenstion.
then load up your memcard in your dexdrive (still using PSXgameedit) and add the single save file. Save and you're done !
I've done it a couple of time in both ways.
Use PSXGameEdit (http://www.moberg-dybdal.dk/psxge/) to extract the single save file you want to transfer from ePSXe's memcard file (you have to rename to the correct extenstion.
then load up your memcard in your dexdrive (still using PSXgameedit) and add the single save file. Save and you're done !