If the ERP field is recoverable in a BOM, you can insert a name with a column for this field. (insert / table / nomenclature then you add your ERP code field if it is not in your default nomenclatures)
If your parts are checked out, you can change the property by double-clicking on the BOM box inserted in your 3d assembly (or MEP) and SW updates the property in the part.
If you have a way to sort your SW nomenclature and your excel file on the same column (plan number for example) you are in the same order so it can go quite quickly at the copy/paste level.
I just tried under SW 2014: you can copy / paste multi box if you have the same number of cells selected in SW and excel. So if you manage to make an exact sorting the manipulation is done in 2 clicks :-)
Without admin rights you will be able to do a lot else otherwise I think.
The simplest is the froussel one, which does not require external software (admin rights) or macros to test. On the other hand, I didn't think that the SW --> epdm link was so simple. Anyone with a cut and paste modifies Plan No., Designation, Counter...
The SW --> Epdm link is indeed quite simple but to say that anyone can modify the values of the variables ...
The security side is managed on the Epdm side and, depending on the settings and the rights given to users and/or groups, it is easy to ensure that no more variables can be modified without respecting a certain process, so the values modified in SW may not be taken into account when the file is archived in Epdm.